Switch to POCL

[vchuravy]

The outstanding

• POCL@v7 Switch to pocl_jll@v7 #599
• printf support Use Printf to report errors from POCL #592
• Switch to pocl_standalone PoCL: Add standalone (OpenCL-less) variant JuliaPackaging/Yggdrasil#11166
  • Renaming issue in build
• Distentagle SPIRVIntrinsics: Currently we inherit quirks from OpenCL https://github.com/JuliaGPU/KernelAbstractions.jl/blob/main/src/pocl/device/quirks.jl but this uses the same method table as OpenCL
• Test OpenCL and KA together to ensure that we have no hidden conflicts.

cc: @maleadt