Find a better way to install and update addons

[A248]

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• There is no duplicate feature request.

Description

A lot of users have ran into linkage errors due to not upgrading their addon jars when they upgraded LibertyBans.

We could, for example, bundle addon jars into the main jar. Then a command such as /libertybans addon install <addon> would extract the addon and prompt the admin to restart the server. Later, we can check the shasum of addon jars and update them if necessary.

The purpose of addons is to organize features to make the codebase and functionality more approachable to developers and users. Their separation is not intended to reduce jar sizes.