[v1] Migration to slash commands

[Karitham]

Why

This issue is here to track the progress of implementing slash commands, which will bring the bot to its 1.0.0.

The goal is to unify the experience of using the bot, and to have it be simpler to use.

It's also a necessity since the bot is now in more than a hundred guilds, and since discord has restricted message listen permissing, using priviledged intents is not worth it

Tasks

• [x] Rolls
  • [x] Basic functionality
  • [x] Cooldowns
  • [x] Token system
• [x] Discard unwanted characters for token #82
• [x] Tests
  • [x] Mock DB
  • [x] Mock Anilist
• [x] Search
  • [x] Anime
  • [x] Manga
  • [x] Char
  • [x] User
• [x] Roll
• [x] List
  • [x] Include a link to the gui ?
  • [x] Buttons for navigation of the embed
  • [x] #51
• [ ] Trade
  • [x] Basic functionality
  • [ ] Ability to give multiple characters
  • [ ] #69
  • [ ] #68
• [ ] Profile
  • [x] Viewing
  • [x] Quote
  • [x] Favorite
  • [ ] Public flag (#69)
  • [x] Anilist profile URL
  • [x] #74
• [x] Verify
  • [ ] Ability to verify multiple characters

[Karitham]

Mostly done, closing this in favor of individual issues