Add capability based HIP device library link

[linehill]

Add a mechanism to link in HIP device library implementations based on target capabilities quaried at runtime (rtdevlib). Using floating-point atomic add operations and their fall-backs as an use case.

Other changes:

• Add checks for atomicAdd() and atomicExch().

• OpenCL: Remove redundant OpenCL declarations.

• Use built-in float/double atomic_exchange*() without cl_ext_float_atomics (they don't require the extension).

• Don't give warnings about undefined symbols starting with __chip_ which are given for symbols defined in rtdevlib.

[linehill]

Todo:

• [x] Fix regressions (was: Investigate/fix issue occurring on POCL).

[pjaaskel]

Although this is a bit intrusive, shall we consider this for 1.1 as it potentially helps portability?

[pvelesko]

rebased on main