Fix generic signature issue when calling non generic method of closed generic type

[buyaa-n]

The method signature populated incorrectly for non generic method that declared within generic type and uses the generic parameters as return type or parameter.

For example, return type of ReadonlySpan<T>.Slice(int) method of an ReadonlySpan<char> instance should be closed generic ReadonlySpan<T> not ReadonlySpan<char>:

Fixes #96469

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Issue Details

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The method signature populated incorrectly for non generic method that declared within generic type and uses the generic parameters as return type or parameter.

For example, return type of ReadonlySpan<T>.Slice(int) method of an ReadonlySpan<char> instance should be closed generic ReadonlySpan<T> not ReadonlySpan<char>:

Fixes #96469

Author:	buyaa-n
Assignees:	-
Labels:	area-System.Reflection.Emit
Milestone:	-