missing testing for cl_ext_float_atomics

[bashbaug]

This issue is to track missing tests for the cl_ext_float_atomics extension.

There is some testing for these extensions in the Vulkan CTS.

There are also some tests in the Intel Cassian test framework, see: intel/cassian@239de5d

A good first step would be to evaluate what is tested by the other frameworks, see what may be useful for the OpenCL CTS, and write up a brief test plan.