Add Expander fast paths for expressions used in .NET SDK 9

[YuliiaKovalova]

Fixes #10398

Context

Is fastpath isn't added for the method, it gets resoled by using reflection that is an expensive operation.
Since the covered methods are actively used by the main customers, they were added to MSBuild.

Changes Made

Add the method from the linked tickets.

Testing

Covered with unit tests.

[baronfel]

This LGTM, thank you for doing this so quickly! For future-us, is there a point at which we would want to switch from a series of if/else for matching to something more like a switch/dictionary lookup?

[rainersigwald]

For future-us, is there a point at which we would want to switch from a series of if/else for matching to something more like a switch/dictionary lookup?

Yeah I think there's a fair amount of room for tweaking here--personally I'd lean toward "make it generated from data" first, because that could let us use some of the sneakier "match to a set of strings" techniques.

[YuliiaKovalova]

This LGTM, thank you for doing this so quickly! For future-us, is there a point at which we would want to switch from a series of if/else for matching to something more like a switch/dictionary lookup?

Oh, definitely yes!
#9975