Add ObsoletedInOSPlatform attribute support in Platform Compat Analyzer

[buyaa-n]

We have added ObsoletedInOSPlatform Attribute in 7.0 recently, now need to add the analyzer support for this in PlatformCompatibilityAnalyzer. By the approved API:

• the warnings for obsoleted should have different diagnostic ID
• optional Message and Url properties that should be appended to the existing message.
• optional Message property is added to the UnsupportedOSPlatform attribute which also needs update in the analyzer

1. Call sites having ObsoletedInOSPlatform or UnsupportedOSPlatform attributes with greater than or equal version could suppress obsoleted warnings
2. Same as unsupported attribute diagnostic the obsoleted diagnostics could be guarded with negated OperatingSystem APIs (for example: if (!OperatingSystem.IsLinux())
3. Also could be guarded with an API that annotated with UnsupportedOSPlatformGuard attribute having matching platform/version, same for negated SupportedOSPlatformGuard
4. No warning if the obsoleted platform and version is not in the call site supported range. Same as UnsupportedOSPlatform no warning for cross platform build in case the platform is not included in MSBuild SupportedPlatforms list
5. Warning message structure is same as the existing warnings, user message and/or Url will be appended at the end of each platform/version
6. MacOS == OSX and iOS is MacCatalyst relations would work same as how it does for unsupported scenarios

Fixes #6081

[codecov]

Codecov Report

Merging #6082 (fe9829d) into main (805420e) will increase coverage by 0.00%.
The diff coverage is 96.44%.

@@           Coverage Diff            @@
##             main    #6082    +/-   ##
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  Coverage   96.04%   96.05%            
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  Files        1338     1339     +1     
  Lines      308692   309416   +724     
  Branches     9824     9855    +31     
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+ Hits       296497   297198   +701     
- Misses       9817     9833    +16     
- Partials     2378     2385     +7     

[jeffhandley]

I left a few fit-and-finish and test recommendations, but the implementation looks good.

[jeffhandley]

Looks good. I only saw a few test code comments that are out of date with the message format.