Deprecate onboard-grant

[maxwofford]

This is now all in https://github.com/hackclub/onboard?tab=readme-ov-file#getting-started, and might be redundant. Not sure what links to this jam though, so creating a ticket to check first.

[jaspermayone]

Hey @maxwofford,

I don't actually see where this links anymore... @SerenityUX may have further clarification but I think we can just remove the files.