Implement an internal time type and Clock trait

[hansl]

This will add the capacity for the entire engine to mock time during tests. No impact on performance should be noticeable.

Fixed #4144

[codecov]

Codecov Report

Attention: Patch coverage is 61.40351% with 22 lines in your changes missing coverage. Please review.

Project coverage is 53.56%. Comparing base (6ddc2b4) to head (6e6d34c).
Report is 356 commits behind head on main.

Files with missing lines	Patch %	Lines
core/engine/src/context/time.rs	68.29%	13 Missing ⚠️
core/engine/src/context/mod.rs	37.50%	5 Missing ⚠️
core/engine/src/object/builtins/jsdate.rs	0.00%	3 Missing ⚠️
core/engine/src/builtins/date/mod.rs	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4149      +/-   ##
==========================================
+ Coverage   47.24%   53.56%   +6.31%     
==========================================
  Files         476      488      +12     
  Lines       46892    48923    +2031     
==========================================
+ Hits        22154    26204    +4050     
+ Misses      24738    22719    -2019     

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