Convert H5Z*.jl packages into package extensions #1995

Job	Run time
julia 1.6 - ubuntu-20.04 - x64 (system libhdf5 + mpich)	2m 37s
julia 1 - ubuntu-20.04 - x64 (system libhdf5 + mpich)	2m 44s
julia 1.6 - ubuntu-latest - x64	2m 30s
MAT.jl - julia 1 - ubuntu-latest - x64	1m 21s
julia 1 - ubuntu-latest - x64	2m 25s
JLD.jl - julia 1 - ubuntu-latest - x64	2m 53s
julia 1 - macOS-latest - x64	3m 25s
julia 1 - windows-latest - x64	3m 15s
julia 1 - windows-latest - x86	4m 31s
julia 1.11-nightly - ubuntu-latest - x64	3m 9s
julia 1.11-nightly - macOS-latest - x64	4m 12s
julia 1.11-nightly - windows-latest - x64	3m 58s
julia 1.11-nightly - windows-latest - x86	4m 10s
julia nightly - ubuntu-latest - x64	3m 22s
julia nightly - macOS-latest - x64	3m 50s
julia nightly - windows-latest - x64	3m 56s
	52m 18s

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