Refactor TimeZoneConverter to remove NodaTime dependency

* Refactor the `TimeZoneConverter` class to eliminate dependencies on the `NodaTime` library, now using `TimeZoneInfo` from NET8.0 framework.
* Simplify the constructor to require only an IANA timezone ID and an optional `CultureInfo` object.
* Update `ToZonedTime` and `ToUtc` methods for timezone conversions using `TimeZoneInfo`.
* Replace `ZonedTime` return value with `IZonedTimeInfo` interface.
* Remove `NodaTime` package reference from `Axuno.Tools.csproj`.
* Add `GetSystemTimeZoneList`, `GetIanaTimeZoneList`, and `CanMapToIanaTimeZone` methods.
* Update `IZonedTimeInfo` interface with additional properties and fully qualified names.
* Update test methods to `TimeZoneConverterTests` for handling unknown timezone IDs and default culture usage.
* Update `TimeZoneConverterTests` to reflect the refactored `TimeZoneConverter` class.
* Bump version to v7.2.1

Axuno.Tools.Tests/DateAndTime/TimeZoneConverterTests.cs

@@ -1,6 +1,5 @@
 using System.Globalization;
 using NUnit.Framework;
-using NodaTime;
 
 namespace Axuno.Tools.Tests.DateAndTime;
 
@@ -9,14 +8,33 @@ public class TimeZoneConverterTests
 {
     private static Axuno.Tools.DateAndTime.TimeZoneConverter GetTimeZoneConverter(string culture)
     {
-        var tzc = new Axuno.Tools.DateAndTime.TimeZoneConverter(
-            new NodaTime.TimeZones.DateTimeZoneCache(NodaTime.TimeZones.TzdbDateTimeZoneSource.Default),
-            "Europe/Berlin",
-            CultureInfo.GetCultureInfo(culture),
-            NodaTime.TimeZones.Resolvers.LenientResolver);
+        var tzc = new Axuno.Tools.DateAndTime.TimeZoneConverter("Europe/Berlin", CultureInfo.GetCultureInfo(culture));
         return tzc;
     }
 
+    [Test]
+    public void UnknownTimeZoneId_ShouldThrow()
+    {
+        // Act, Assert
+        Assert.That(() =>
+        {
+            _ = new Axuno.Tools.DateAndTime.TimeZoneConverter("unknown-time-zone", CultureInfo.CurrentCulture);
+        }, Throws.Exception.TypeOf<TimeZoneNotFoundException>());
+    }
+
+    [Test]
+    public void UseCurrentCulture_IfCultureIsMissing()
+    {
+        // Arrange
+        var utcDateTime = new DateTime(2022, 1, 1, 12, 0, 0, DateTimeKind.Utc);
+
+        // Act
+        var convertedDateTime = new Axuno.Tools.DateAndTime.TimeZoneConverter("Europe/Berlin").ToZonedTime(utcDateTime)!;
+
+        // Assert
+        Assert.That(convertedDateTime.CultureInfo.TwoLetterISOLanguageName, Is.EqualTo(CultureInfo.CurrentUICulture.TwoLetterISOLanguageName));
+    }
+
     [Test]
     public void ConvertUtcToTimeZoneStandard_ShouldReturnCorrectDateTime()
     {
@@ -40,7 +58,7 @@ public void ConvertUtcToTimeZoneStandard_ShouldReturnCorrectDateTime()
             Assert.That(convertedDateTime.Abbreviation, Is.EqualTo("MEZ"));
             Assert.That(convertedDateTime.IsDaylightSavingTime, Is.False);
             Assert.That(convertedDateTime.DateTimeOffset.Offset, Is.EqualTo(new TimeSpan(0, 1, 0, 0)));
-            Assert.That(convertedDateTime.BaseUtcOffset, Is.EqualTo(new TimeSpan(0,1,0,0)));
+            Assert.That(convertedDateTime.BaseUtcOffset, Is.EqualTo(new TimeSpan(0, 1, 0, 0)));
         });
     }
 
@@ -173,14 +191,22 @@ public void ConvertTimeZoneToUtc_ShouldReturnNull_WhenDateTimeOfAnyKindIsNull()
         // Assert
         Assert.That(convertedDateTime, Is.Null);
     }
+
     [Test]
     public void GetTimeZoneList_ShouldReturnTimeZoneList_WhenTimeZoneProviderIsNull()
     {
-        // Arrange
-        IDateTimeZoneProvider? timeZoneProvider = null;
+        // Act
+        var timeZoneList = Axuno.Tools.DateAndTime.TimeZoneConverter.GetSystemTimeZoneList();
 
+        // Assert
+        Assert.That(timeZoneList, Is.InstanceOf<IReadOnlyCollection<string>>());
+    }
+
+    [Test]
+    public void GetIanaTimeZoneList_ShouldReturnTimeZoneList_WhenTimeZoneProviderIsNull()
+    {
         // Act
-        var timeZoneList = Axuno.Tools.DateAndTime.TimeZoneConverter.GetTimeZoneList(timeZoneProvider);
+        var timeZoneList = Axuno.Tools.DateAndTime.TimeZoneConverter.GetIanaTimeZoneList();
 
         // Assert
         Assert.That(timeZoneList, Is.InstanceOf<IReadOnlyCollection<string>>());

Axuno.Tools/Axuno.Tools.csproj

@@ -9,7 +9,6 @@
     <ImplicitUsings>enable</ImplicitUsings>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="NodaTime" Version="3.1.12" />
     <PackageReference Include="NuGetizer" Version="1.2.3">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>

Axuno.Tools/DateAndTime/IZonedTimeInfo.cs

@@ -8,15 +8,20 @@ namespace Axuno.Tools.DateAndTime;
 public interface IZonedTimeInfo
 {
     /// <summary>
-    /// Gets the <see cref="CultureInfo"/> used for localization.
+    /// Gets the <see cref="System.Globalization.CultureInfo"/> used for localization.
     /// </summary>
     CultureInfo CultureInfo { get; }
 
     /// <summary>
-    /// Gets the IANA timezone ID related to the <see cref="DateTimeOffset"/>.
+    /// Gets the IANA timezone ID related to the <see cref="System.DateTimeOffset"/>.
     /// </summary>
     string TimeZoneId { get; }
 
+    /// <summary>
+    /// Gets the <see cref="System.DateTimeOffset"/> which is set based on the timezone offset to UTC.
+    /// </summary>
+    DateTimeOffset DateTimeOffset { get; }
+
     /// <summary>
     /// Gets the generic name for the time zone.
     /// </summary>
@@ -33,17 +38,17 @@ public interface IZonedTimeInfo
     string DisplayName { get; }
 
     /// <summary>
-    /// Gets the name of the timezone related to the <see cref="DateTimeOffset"/>.
+    /// Gets the name of the timezone related to the <see cref="System.DateTimeOffset"/>.
     /// </summary>
     string Name { get; }
 
     /// <summary>
-    /// Gets the timezone abbreviation related to the <see cref="DateTimeOffset"/>.
+    /// Gets the timezone abbreviation related to the <see cref="System.DateTimeOffset"/>.
     /// </summary>
     string Abbreviation { get; }
 
     /// <summary>
-    /// Gets whether the timezone related to the <see cref="DateTimeOffset"/> is daylight saving time.
+    /// Gets whether the timezone related to the <see cref="System.DateTimeOffset"/> is daylight saving time.
     /// </summary>
     bool IsDaylightSavingTime { get; }