Unbundle SPL into separate repositories

[steveluscher]

The job is to unbundle the programs in SPL into their own repositories housing the code for the on-chain program, CLI, the generated JavaScript client (IDL, Kinobi description, and NPM module), and whatever else.

Greater separation here will make it easier to triage feedback (ie. via GitHub issues), code contributions (ie. pull requests), and to act on advisories (ie. Dependabot).

After each repo is created, move GitHub issues and PRs from here to there.

cc/ @lorisleiva

[lorisleiva]

I can't self-assign here but as soon as I have permission to create new repositories, I can start working on that.