rhel: Add RHCOS content set location to repositoryscanner

[Maddosaurus]

RHCOS stores the content-set files in /ur/share/buildinfo instead of /root/buildinfo. As RHCOS and RHEL share CVE feeds, we can extend this scanner instead of building a new one for RHCOS.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 60.00000% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 56.24%. Comparing base (4c5aa9e) to head (1f2be5f). Report is 4 commits behind head on main.

Files	Patch %	Lines
rhel/repositoryscanner.go	60.00%	1 Missing and 1 partial :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1346      +/-   ##
==========================================
- Coverage   56.24%   56.24%   -0.01%     
==========================================
  Files         266      266              
  Lines       16838    16842       +4     
==========================================
+ Hits         9471     9473       +2     
- Misses       6402     6403       +1     
- Partials      965      966       +1     

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[Maddosaurus]

@crozzy I've bumped the Version, and introduced an additional test to ensure the scanner doesn't panic, even if the very same file exists in both locations (which should be highly unlikely).