[FEATURE] Add bpt repo remove --if-missing={ignore,fail}

[maxtruxa]

Describe the scenario and circumstances that should be addressed

While it "feels" good that bpt repo remove doesn't report an error when the package to be removed doesn't exist anyways, it's also easy to mistype the package ID without being informed about it.

Describe the solution you'd like

Introduce a new --if-missing option to bpt repo remove, similar to bpt repo import --if-exists. Possible values might be ignore (same behavior as right now) and fail (which should issue an error if the package doesn't exist).

IMO the default behavior should be changed to fail as well because it's the safer default, but that I don't care about as much.

Additional context

I'm currently working on an HTTP API for a bpt repo and intend to report an error if the client attempts to delete a non-existent package (except if the client explicitly states that it doesn't care). The current workaround is checking that the package exists through bpt repo ls before attempting to remove it. This feels clunky, has to be manually guarded against races, and obviously doesn't help CLI usage of bpt.

[vector-of-bool]

This has bitten me a few times. It is reasonable to add this.