Bug description

VSTHRD200 does not trigger on local functions.

Repro steps

public class MyClass
{
    public void Foo()
    {
        async Task Bar()
        {
        }
    }
}

Expected behavior

VSTHRD200 should trigger on function Bar

Actual behavior

VSTHRD200 did not trigger on function Bar

• Version used:
  Microsoft.VisualStudio.Threading.Analyzers: 17.4.27

Additional context