Support multiple -add_comment arguments

[camillobruni]

This makes it a bit nicer to annotate profiles when using external tools.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 67.35%. Comparing base (294ebfa) to head (282fd68).
⚠️ Report is 9 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #987   +/-   ##
=======================================
  Coverage   67.35%   67.35%           
=======================================
  Files          44       44           
  Lines        7792     7792           
=======================================
  Hits         5248     5248           
  Misses       2112     2112           
  Partials      432      432           

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[aalexand]

I think the test implementation testFlags is different from internal/driver/flags.go. I'm not sure GoFlags there support multiple flags properly. Could you test that manually? Please also check that this change does not make the comma a separator as we want something like -add_comment=hello,world to add one comment, not two.