Add builds & dynamic loading for four targets

[KendallWeihe]

• Add bindings/tbdex_uniffi/libtargets for building the 4 targets we support
• Add test for loading shared library based on system architecture
• Add GitHub CI workflow for testing the loading of the shared library across our targets
• Add the shared lib binaries for each of the four
• Add SystemArchitecture.set() in bound/kt and add calls in all relevant places (this ensures the proper system architecture is detected prior to UniFFI's codegen'd Native.load()
• Add assumption for all local dev right now to be aarch64-apple-darwin 🚧 we'll make this dynamic later, but right now all major developers are running Apple silicon
• Add print statements to example PFI

[KendallWeihe]

I'm moving this to a Draft, I want to reconsider a few things

[KendallWeihe]

@nitro-neal heads up on this PR because I went a slightly different direction then when we last spoke. I decided to use the GitHub Workflow specifically for testing the loading of the shared library across the four targets, and building has been moved to bindings/tbdex_uniffi/libtargets. We'll probably still build the shared libs in the pipeline in due time, but for now this enables us to move quicker -- we can debug builds locally, and use the pipeline for a quick <60 seconds test to ensure the build is still compatible. The alternative is 10+ minute process times when using the pipeline. I think we can get the best of both worlds in due time but for now this is ideal.

Another thing, I couldn't quite get the RustCore abstraction to work around the UniFFI code gen. For now, I went with SystemArchitecture.set() and am calling it in all the relevant places. There may be a more eloquent way to do this, but this works.

[nitro-neal]

Maybe in the future this can be an env variable instead of sed ing

[nitro-neal]

There must be a way to call this when someone does an import on tbdex-kt..

like maybe a wrapper around the entire sdk thats like this:

class TbdexWrapper {
    companion object {
        init {
           SystemArchitecture.set()
        }
    }
}

[nitro-neal]

Probably other ways too, we can experiment with it

[nitro-neal]

Its pretty ugly with the SystemArchitecture.set() I think first priority would be to figure out how to do it in just one place on init somewhere