Add ability to view dependencies and dependents on a plugin page

[stefvanschie]

As discussed in the PaperMC Discord guild, it'd be a good idea to show both dependencies for the plugin you're currently looking at as well as dependents of this plugin. The former allows users who are looking at a plugin to see which other plugins they need to install to make the plugin work. The latter allows users to easily see what other extensions/add-ons for the plugin are available, as those would be dependent on the "main" plugin. This would also help with plugins like Vault in seeing which economy, chat and permission plugins are compatible with it. The dependents may need to get a search feature, since dependents can quickly grow to large amounts. Relevant Discord discussion starts here: https://discord.com/channels/289587909051416579/746367733699969104/789113624575868929.

[MiniDigger]

"this projects uses those projects (hard/soft) and is used by these projects (hard/soft)"

[MiniDigger]

maybe as a dedicated page, github style: https://github.com/thelounge/thelounge/network/dependents?dependent_type=REPOSITORY

[webcrawls]

maybe as a dedicated page, github style: https://github.com/thelounge/thelounge/network/dependents?dependent_type=REPOSITORY

i'd be okay with this, personally - curseforge did something similar to this with mod dependants/dependencies (though their UI wasn't great)

i'd like if you could "pin" hard dependencies in a sidebar or something like that - some way to make it it obvious what first-party addons are recommended/supported