`ape plugins install` from tag, branch, repo, or pull request

[banteg]

Overview

foundryup has a very handy functionality which allows installing a version from a branch, a tag, a forked repo, or a pull request. this could be a nice shorthand for ape plugins, so i could say something like ape plugins install etherscan --pr 42.

Specification

add --tag, --pr, --branch, --repo options to ape plugins install which would install a version from source instead of from pypi.

Dependencies

i think this can be handled by pip alone, since it supports git protocol.

[fubuloubu]

Foundry needs this, because it's simply not possible otherwise to hack in functionality into the binary without recompiling it, but pip is dynamic, and I think anyone competent who is contributing or using un-released code should understand they can do anything they want to to their environment with pip. It's a few extra steps for them, but I think this feature would be a lot more trouble than it's worth to provide. ape plugins is a streamlined wrapper around pip intended only for production-supported plugins.

We could definitely add a little clarity to the contributing docs to inform people that there are many ways of using pip to achieve the desired result