feat: add support for user-installable apps

[SerenModz21]

This PR depends on the following:

• https://github.com/sapphiredev/framework/pull/782
• https://github.com/sapphiredev/utilities/pull/799
• https://github.com/sapphiredev/plugins/pull/622

~~What commands should I allow to be used from a user-install and which ones should I limit to guild-installs? Right now, I've only done the ping command.~~

Update: After looking at the Discord docs, I realized that I don't need to state explicitly all the integration types and contexts, due to the defaults. Therefore, the current implementation of the ping command is redundant. Due to the ping command being the only interaction-based command, what do you think I should do? Create another command to test providing integrationTypes and contexts for a guild-install command or should I do something else?