Cache parameter writer lookups

[SteveSandersonMS]

See description at #24466.

This improves the ComplexTable benchmark by about 7.3% (though the op count improves by 17%).

[pranavkm]

There's a ReferenceEqualityComparer<T> type in 5.0 you could use. You can avoid create the type type. Basically,

Suggested change

	_writerCache = new ConcurrentDictionary<StringObjectIdentityKey, IPropertySetter?>();
	_writerCache = new ConcurrentDictionary<string, IPropertySetter?>(ReferenceEqualityComparer<string>.Instance);

[SteveSandersonMS]

Great, thanks for the tip! I switched over to this and not only does it save code, but it reduces the instruction count by another 1% on the ComplexTable benchmark (probably because it no longer has to call the constructor or field setter for my custom type).

[pranavkm]

One additional optimization we could make is to stash the the WritesForType as an internal property on ComponentBase and avoid the dictionary lookup there.

if (target is ComponentBase component)
{
  component.Writer ?? = new WritersForType(targetType);
  _writer = component.Writer;
}
else
{
 // old code
}

[SteveSandersonMS]

Thanks for the suggestion. Since this didn't show up in the profile traces as a hot path, I'd prefer not to add an optimization for it.

I guess that doing the lookup for this dictionary is relatively cheap because component.GetHashCode() is much cheaper than computing a string hash.