Report MA0179 on the array-returning GetCustomAttributes overloads

[meziantou]

What

MA0179 (Use Attribute.IsDefined instead of GetCustomAttribute(s)) did not report the GetCustomAttributes overloads that return an array when they are followed by .Any() or .Count():

_ = member.GetCustomAttributes(typeof(ObsoleteAttribute), false).Any();   // was not reported
_ = member.GetCustomAttributes<ObsoleteAttribute>().Any();                // was reported

Why

IsGetCustomAttributesInvocation did operation as IInvocationOperation. The array-returning overloads (MemberInfo.GetCustomAttributes(Type, bool), the static Attribute.GetCustomAttributes methods, …) produce an implicit IConversionOperation (Attribute[]/object[] to IEnumerable<T>) around the invocation when they are passed to Enumerable.Any or Enumerable.Count, so the cast yielded null. Its singular twin IsGetCustomAttributeInvocation already called UnwrapConversions() first.

These are the overloads available on netstandard2.0 and the ones used by older code, so the rule was silent exactly where the older API is in use.

The .Length comparisons were already reported: there the array is the direct instance of the Length property reference, with no conversion in between.

Changes

• UseAttributeIsDefinedAnalyzer: unwrap the conversions in IsGetCustomAttributesInvocation.
• UseAttributeIsDefinedFixer: the same unwrapping in the Any() and Count() paths. Without it, the fixer would be offered on the newly reported patterns and return the document unchanged.
• docs/Rules/MA0179.md: added the array-returning overload to the examples.
• 4 tests: MemberInfo.GetCustomAttributes(Type, bool).Any(), Attribute.GetCustomAttributes(member, Type).Any(), .Count() > 0 with a named inherit argument, and a negative case checking that a user-defined GetCustomAttributes extension method followed by .Any() is still not reported (the conversion unwrapping must not weaken the check added in Do not report MA0179 on user-defined GetCustomAttribute(s) methods #1386).

Verification

• Reverting only the two source files makes the 3 new positive tests fail and leaves the negative one passing; with the fix they all pass (33/33 in UseAttributeIsDefinedAnalyzerTests).
• Full suite on all 5 Roslyn versions: 19278 passed, 0 failed.
• dotnet run --project src/DocumentationGenerator exits 0 with no further markdown changes.