[Task] Implement voice summaries

[No767]

Task Description

This idea was introduced by an conversation that I had with Triona, and would probably put this on Kumiko. The idea is to summarize what happens in a VC (not the contents). Here is what will happen in a step by step process

User one joins vc, and then user two also joins the vc. They talk for a while, and then exit the VC. The bot detects when there is someone (at least one user) in the VC, and then waits for others to join. On updating the voice state, the bot stores the info, like who joined, etc. Once everyone has left, a summary will be posted and stored on the database of what users joined, how long it took, etc. This tool can be used by moderators to make informed decisions pertaining to a certain call that may had some issues, such as arguments and others.