lib: make getCallSites sourceMap option truly optional

[jasnell]

When calling the util.getCallSites(...) API, if the options argument is omitted, then the options.sourceMap option is defaulted to false. However, if any empty options is passed, it would throw an error if sourceMap was not explicitly given. This relaxes that so that sourceMap can be left unspecified.

For instance, before this commit, getCallSites({}) would throw an error.

Also, add more test coverage of this.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.23%. Comparing base (9df0ff7) to head (0712421).
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #57388   +/-   ##
=======================================
  Coverage   90.23%   90.23%           
=======================================
  Files         630      630           
  Lines      185200   185204    +4     
  Branches    36233    36238    +5     
=======================================
+ Hits       167108   167127   +19     
+ Misses      11056    11054    -2     
+ Partials     7036     7023   -13     

Files with missing lines	Coverage Δ
lib/util.js	97.73% <100.00%> (+0.01%)	⬆️

... and 21 files with indirect coverage changes

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[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/65662/