Proposal: implement a plug-in system for the CLI

[andreibancioiu]

Allow community developers to register and install their own tools within the mxpy CLI hub.

From the perspective of mxpy users

Example:

$ mxpy plugins install some-github-organization/some-repository@tag
> You are about to install the plugin "some plugin", which can theoretically harm your computer or steal secrets, just as any malicious program or software is able to.
> Do you trust this third-party plugin, and its authors? (y/n)

$ mxpy some-command ...
> You are about to execute a command implemented by the third-party plugin "some plugin". Proceed? (y/n)
...

$ mxpy some-command ... --confirm-trusted-plugin
...

From the perspective of plugin developers

TBD