This commit unifies target environment queries into a new wrapper
class spirv::TargetEnv and shares across various places needing
the functionality. We still create multiple instances of TargetEnv
though given the parent components (type converters, passes,
conversion targets) have different lifetimes.
In the meantime, LowerABIAttributesPass is updated to take into
consideration the target environment, which requires updates to
tests to provide that.
Differential Revision: https://reviews.llvm.org/D76242
58df5e6d9a