T5374: Add system option time-format 12 or 24 hours

[sever-sever]

Change Summary

Ability to set locale time format 12|24-hour

set system option time-format 12-hour|24-hour

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://vyos.dev/T5374

Component(s) name

time

Proposed changes

How to test

vyos@r14:~$ date
Tue Aug  1 12:33:45 PM EEST 2023
vyos@r14:~$ 

Set 24-hour format and re-login to the system

vyos@r14# set system option time-format 24-hour 
[edit]
vyos@r14# commit
[edit]
vyos@r14# exit
Warning: configuration changes have not been saved.
exit
vyos@r14:~$ logout
Connection to 192.168.122.14 closed.
sever@sever:~$ sr14
Warning: Permanently added '192.168.122.14' (ED25519) to the list of known hosts.
Welcome to VyOS!

vyos@r14:~$ 
vyos@r14:~$ date
Tue  1 Aug 12:34:09 EEST 2023
vyos@r14:~$ 

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly