feat: add buck2

[Conarius]

No description provided.

[williamboman]

Hello and thanks for the PR (and apologies for late review)! This seems¹ to be a package that exceeds the scope of the core registry. An example of such a package is something that installs an entire language toolchain or platform through either a single or multiple binaries. Management of such packages through Mason has a history of causing issues/confusion for both users and the maintainers of the software themselves. You can always host your own packages through your own registry, see https://github.com/williamboman/mason-registry-playground/ for a starting point.

^{1 - please let me know if you disagree with my assessment}