Remove code paths that depend on RMM_STATIC_CUDART

[robertmaynard]

Description

We can remove the optimizations around CUDA_STATIC_RUNTIME and instead see if the function is already in the process space so that RMM doesn't need to have any build context to run properly

Fixes #1679

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[harrism]

Are existing tests sufficient to cover this?

[robertmaynard]

Are existing tests sufficient to cover this?

I will add explicit tests that control the type of cudart we are using to verify these chages

[robertmaynard]

Did more testing today and realize that more work is needed. With this PR we are getting all the symbols required at link time, but the dlsym with RTLD_DEFAULT is failing for a couple of the use cases. The tests still pass in CI since a libcudart.so exists on the machine.

Need more time to figure out what is going wrong.

[vyasr]

In what contexts is this failing? I assume it's a statically linked case, so the symbols cannot have been (dynamically) loaded with RTLD_LOCAL in a way that would obscure them from this scope.