Updated patch to make it extendable to more selectors
Implemented device_arch and implementation_vendor selectors as well

In D76211#2212203, @jdoerfert wrote:

Are you planning to add support for the actual OpenMP selectors as well?
All the other traits, scoring, etc. I left a comment below that points you to the right place as we have almost all of that already ready to be reused.
On this note, I would recommend you take a look at the OpenMP 5.1 draft, it contains proper wording for a dynamic context extension, and we will need support in the declare variant as well. That means we need to allow dynamic expressions in OMPTraitInfo and similar places eventually anyway.

Updated the test cases.
Fixed an issue where correct code was not generated if directive variant was not provided in when/default clause

Updated the test files

Fixed formatting issues and replaced SmallVector with ArrayRef .

Fixed build error and test files

Adding test case