fix: support interfaces with different name casing

[TimothyMakkison]

• Add StringComparer.OrdinalIgnoreCase to keyCount
• Added name casing test and same name, different signature test

Fixes #1689

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.95%. Comparing base (6ebeda5) to head (b36cd1d).
Report is 168 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1930      +/-   ##
==========================================
- Coverage   87.73%   84.95%   -2.78%     
==========================================
  Files          33       36       +3     
  Lines        2348     2506     +158     
  Branches      294      364      +70     
==========================================
+ Hits         2060     2129      +69     
- Misses        208      299      +91     
+ Partials       80       78       -2     

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