Securise app version and upgrade validate_app

[LiquidITGuy]

First of all, thank you for your contribution! 😄

Hi,
I tried to standardize the $$cap_app_name to check and to fix all the fixed versions without variables and with fixed values.

I added three checks on validate app :

• does the app version exist
• is this variable different than latest
• does the description give a way to know the available tags
  I also use a for of instead of the var i for performance purpose.

To finish I would later create a new command to know which packages are deprecated and from how long

I think this PR is more readable commit by commit.
I hope this could help

Regards

• I have tested the template using the method described in README.md thoroughly
• I have ensured that I put as much default values as possible (except passwords) to ensure minimum effort required for end users to get started.
• I have ensured that I am not using the "latest" tag as this tag is dynamically changing and might break the one-click app. Use a fixed version.
• I have made sure that instructions.start and instructions.end are clear and self-explanatory.
• I've executed the checks if necessary by running npm ci && npm run validate_apps && npm run formatter (If failling run the prettier: npm run formatter-write)
• I will take responsibility addressing any issues that arises as a result of this PR (maintaining this app).

[LiquidITGuy]

The failed check is an unvolontary proof of concept of the new validation 😄