feat: add wit-codegen tool (#15) #5

Job	Run time
build (windows-2022, vcpkg-VS-17, VS-17-Release, ZIP;NSIS, -C Release, build/cmcpp-*.zip build/cm...	23m 46s
build (macos-14, linux-ninja-Release, linux-ninja-Release, TGZ;ZIP, build/cmcpp-*.tar.gz build/cm...	14m 15s
build (ubuntu-24.04, linux-ninja-Release, linux-ninja-Release, TGZ;DEB;RPM, build/cmcpp-*.tar.gz ...	9m 48s
	47m 49s

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