Avoid boxing compiler jobs during kernel resolution

[maleadt]

Kernel resolution constructs a CompilerJob immediately before passing it through an unspecialized compile_or_lookup boundary, which can force the job onto the heap. Allow specialization on the job's target and compiler-parameter types, and keep the method @noinline so its body is not duplicated into callers specialized per kernel. Kernel identity remains a field of the job, so this does not introduce per-kernel specialization or another cache.

Applies the approach from KernelAbstractions.jl#769.

On Julia 1.13 / GPUCompiler 2.5.2 with the Intel CPU OpenCL runtime, warm clfunction resolution dropped from 192 to 32 bytes per call. Kernel launch and all eight existing compilation-cache tests passed, including reflection and redefinition. Two kernels produced one compile_or_lookup specialization.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.43%. Comparing base (9d5a395) to head (4cd4c06).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #482   +/-   ##
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  Coverage   84.43%   84.43%           
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  Files          14       14           
  Lines        1086     1086           
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  Hits          917      917           
  Misses        169      169           

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