refactor(uuid): factor out common symbols into common module

[iuioiua]

This PR moves NIL_UUID into uuid/constants.ts and the remaining symbols implemented in mod.ts into uuid/common.ts.

Towards #4748

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.89%. Comparing base (aa35b35) to head (da66ddb).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4749   +/-   ##
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  Coverage   91.89%   91.89%           
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  Files         484      485    +1     
  Lines       41296    41300    +4     
  Branches     5319     5319           
=======================================
+ Hits        37947    37951    +4     
  Misses       3292     3292           
  Partials       57       57           

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[kt3k]

It makes sense to export common utils from @std/uuid/common. LGTM