feat: pure_12hr_system_time option for 12 hour system time

[ThatOneCalculator]

Specs

12 hour system time, if system time is enabled

New config in conf.d/pure.fish

_pure_set_default pure_12hr_system_time false

Documentation

Usage

❯ set --universal pure_12hr_system_time true

Acceptance Checks

• Documentation is up-to-date:
  • Add entry in feature list of README.md ;
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• Tests are passing (we can help you 🤗 ):
  • Configs are tested (cf. tests/_pure.test.fish) ;
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• Customization is available ;
• Feature is implemented.

[edouard-lopez]

Thanks for the PR!
issue: the implementation is far too specific, and we don't want to re-implement every date-supported format.

suggestion: A simpler solution would be to

1. set the format in a universal variable (cf. conf.d/pure.fish) like pure_show_system_time_format ;

2. set its default to +%T (so we preserve existing behaviour) ;

3. then users can simply override this variable on their config with

   set --universal pure_show_system_time_format '+%I:%M:%S %p'
   

todo: add a sample in the doc

[ThatOneCalculator]

Done! Made the variable pure_system_time_format since that reads better imo, I could change it if you want though