fix CA2021 false positives

[fowl2]

Can't say I really understand this that well, but adds the test case and fixes #7153 without breaking anything else as far I can tell.

---

The code was previously using ITypeSymbol property AllInterfaces which says the seemly relevantly:

// This is not quite the same as "all interfaces of which this type
// is a proper subtype"
However, I couldn't find any sort of "proper subtype" API.

So this change sprinkles some OriginalDefinition calls around, and switches to using DerivesFrom - which calls OriginalDefinition on all the interface symbols before checking equality.

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (d0311fb) 96.44% compared to head (b87e72e) 96.44%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7183      +/-   ##
==========================================
- Coverage   96.44%   96.44%   -0.01%     
==========================================
  Files        1415     1415              
  Lines      338191   338229      +38     
  Branches    11191    11191              
==========================================
+ Hits       326166   326201      +35     
- Misses       9205     9209       +4     
+ Partials     2820     2819       -1     

[buyaa-n]

Can't say I really understand this that well, but adds the test case and fixes #7153 without breaking anything else as far I can tell.

The code was previously using ITypeSymbol property AllInterfaces which says the seemly relevantly:

// This is not quite the same as "all interfaces of which this type
// is a proper subtype"
However, I couldn't find any sort of "proper subtype" API.

So this change sprinkles some OriginalDefinition calls around, and switches to using DerivesFrom - which calls OriginalDefinition on all the interface symbols before checking equality.

I think DerivesFrom works because it checks constraints, not only all interfaces

[buyaa-n]

LGTM, thank you @fowl2 for quick fix