Resolve overloads in TryFindMethod and search inherited interfaces [patch]

[matt-edmondson]

Fixes #155
Fixes #158

What changes

The triage on both issues says to fix them together, so this PR does that. TryFindMethod now searches one hierarchy level at a time, using GetMethods(flags | DeclaredOnly) filtered by name, and stops at the first level that declares the name.

• Overloads (TryFindMethod throws AmbiguousMatchException for overloaded method names instead of returning a result #155): when a level has several overloads, it returns the one with the fewest parameters. A non-generic method beats a generic one with the same number of parameters. Any remaining tie is broken by ordinal order of the method signatures. The method no longer throws AmbiguousMatchException, and it gives the same answer every time for the same type. The rule is documented in the XML <remarks>.
• Interfaces (TryFindMethod returns false for methods an interface inherits from its base interfaces: typeof(IList<int>).TryFindMethod("Add", …) finds nothing #158): when type is an interface, the search covers the interface itself and then type.GetInterfaces(). Inherited interfaces are grouped by how many interfaces they themselves inherit, and the larger groups are searched first, so a derived interface always comes before the interfaces it extends. For example, IList<int>.GetEnumerator resolves to IEnumerable<int>, not the non-generic IEnumerable.

Tests

• The existing TryFindMethodThrowsOnAmbiguousMatchForOverloadedMethod test asserted the bug, so it now checks that the parameterless overload is returned.
• New tests cover string.Split, private overloads on a base class, determinism, one and two levels of interface inheritance, and the IList<int> / ICollection<int> cases from TryFindMethod returns false for methods an interface inherits from its base interfaces: typeof(IList<int>).TryFindMethod("Add", …) finds nothing #158.
• With the fix reverted, all 7 new or changed tests fail. With the fix, the full suite passes (182 tests). The Release build passes on every target framework.

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https://claude.ai/code/session_01P2fpLkFHYU6nd3JVKufVtK

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Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
95.5% Coverage on New Code
0.0% Duplication on New Code

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