Improve performance when configuring fake method

[blairconrad]

AssemblyExtesions.Name creates a new AssemblyName when I don't think it has to.
If I stop:

And garbage collection time drops from 16% to 6%.

Or if you like the diff format:

[thomaslevesque]

Wow. I didn't expect the AssemblyName constructor to be so expensive.

[blairconrad]

Oh. I have a better thing.

[thomaslevesque]

OK... how did you do it ?

[thomaslevesque]

Ah, I see. ProxyUtil.IsProxyType!

[blairconrad]

I marked #1472 as connecting to this issue in case we want to pile on a few more PRs. If you'd rather, I don't mind closing this issue with the one PR and opening more issues (or just sending raw PRs) for other performance work in the area.

[thomaslevesque]

No, I think it's OK to keep this one open for now.

[blairconrad]

This could be a never-ending process, but we've had good results. I think I'll focus my efforts somewhere else for a while.
Closed in #1472, #1476, #1483, #1485, and #1486.

[thomaslevesque]

This change has been released in FakeItEasy 5.0.0.