Remove unreachable and unused overload methods from IntrinsicFunctions

[jrdodds]

Fixes # (issue to be created)

Context

This is a change that was split out from PR #8569 at the request of @rainersigwald.

The change removes type overload methods from IntrinsicFunctions that are unreachable via evaluation and that are unused within the repo.

This is cleanup that could support a future effort to add source generation for the 'fast path' lookup.

Changes Made

Remove long variants of Add, Subtract, Multiply, Divide, and Modulo. Evaluation will always use the double variants.

Testing

Built and ran unit tests on Windows 11 and macOS 12.

Notes

[JanKrivanek]

Looks good - dead code removal

[Forgind]

rainersigwald commented this morning that our documentation says we support longs and made a pigeonhole argument that supporting doubles does not obviate the need to support long. Indeed, I made a very simple test project (see #8698) that demonstrates that MSBuild is indeed flawed in this respect. We're currently not 100% clear on whether we can take this change and just change how we parse the numbers or if we need to explicitly call these overloads but currently aren't.

[jrdodds]

This issue of the unsupported overloads came up in the discussion for #8569 but it is 'new' in this discussion that long must be supported. It does make sense that long should be supported and that parsing only to a double is a defect.

[jrdodds]

Negated by #8710