Add polyfills for Enum.IsDefined<T>(...) and Enum.HasFlag(...)

[Tyrrrz]

No description provided.

[Copilot]

Pull request overview

This PR adds polyfills for two Enum methods that were introduced in later framework versions: Enum.IsDefined<T>(...) (added in .NET 5.0) and Enum.HasFlag(...) (added in .NET Framework 4.0). The polyfills enable these APIs to be used in older framework versions.

Key changes:

• Adds HasFlag instance method polyfill for pre-.NET 4.0 Framework versions
• Adds IsDefined<T> static method polyfill for pre-.NET 5.0 versions
• Updates documentation to reflect the addition of 2 new members (246 total, 184 members)

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
PolyShim/Signatures.md	Updates totals and adds documentation entries for HasFlag and IsDefined<T>
PolyShim/NetCore10/Enum.cs	Implements HasFlag instance method for enum flag checking
PolyShim/Net50/Enum.cs	Implements IsDefined<T> generic method as a wrapper around non-generic version
PolyShim.Tests/Net50/EnumTests.cs	Adds unit test for IsDefined<T> with valid and invalid enum values

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 0.00%. Comparing base (51eae5d) to head (ac9e837).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

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