Cross-bundling

[martinfouilleul]

Enable cross bundling of Orca applications.

• Cross-bundling from macOS to Windows may be straightforward (just have to make the right directory tree).
• Windows to macOS requires setting permission bits in executable and dynamic libraries. We could do this by zipping the app bundle and tweaking the permission bits inside the zip file.

Some resources:

• Libzip: https://libzip.org/documentation/
• ZIP external attributes contain OS-specific file permissions: https://unix.stackexchange.com/questions/14705/the-zip-formats-external-file-attribute

Of course we'd also need to package pre-built binaries for all platforms into a single release. So our release folder may have this structure:

release-xxxxxxxxxx
	bin
		macos
			orca_runtime
			*.dylib
			...
		windows
			orca_runtime.exe
			*.dll
			...
		wasm
			liborca_wasm.a
	orca-libc
	resources
	src

• This requires changes in the orcadev install command and CI release action to combine installs from win/mac
• Changes in orca bundle to add a target option and do the cross-bundling
• Should require no changes on orcadev build command and CI build actions

[rdunnington]

Once we get the build system moved over to zig build, we could even build cross-platform binaries on a single platform and not have to do any "combine" step. The tricky part here is angle and dawn - these are big libs with their own complicated build systems that we probably don't want to port to zig build. Ideally we use prebuilt artifacts so we don't need to deal with it.