add atomic swap support for OpenCL

[SimonDanisch]

I guess the others also ignore ordering?

[codecov]

Codecov Report

❌ Patch coverage is 0% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 51.26%. Comparing base (e60c518) to head (7fdd5cc).
⚠️ Report is 19 commits behind head on main.

Files with missing lines	Patch %	Lines
ext/AtomixOpenCLExt.jl	0.00%	5 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #66       +/-   ##
===========================================
- Coverage   92.95%   51.26%   -41.70%     
===========================================
  Files           6       10        +4     
  Lines         142      277      +135     
===========================================
+ Hits          132      142       +10     
- Misses         10      135      +125     

Flag	Coverage Δ
Pkg.test	51.26% <0.00%> (-41.70%)	⬇️

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