feat: moving away from juniper and sea-orm

[sargon64]

PR to move away from both juniper and sea-orm.

Juniper has been a thorn in my side for quite a while due to it lagging behind in features that asnyc-graphql now provides. It's a similar story with seaORM, where I feel like I'm trying to fight with the ORM to do things that I can do easily in SQL.

And so, I finally decided to bite the bullet and start switching.

I'd like to finish this before trying to resolve [nolink] #85 & #86 as migrating would help with adding those tremendously.

Checklist:

• Switch from juniper to async-graphql
  • Switch from actix-web to poem (the docs for async-graphql-actix seem to be out of date, and don't work + poem seems to be the more supported framework)
• Switch from SeaORM to sqlx
  • Add a migration system for meilisearch (as of right now we've been piggybacking off of seaorm's migraiton system for changes to meili, but It's time to find a diffrent soultion)

[rithik-b]

lgtm (I'm a 10x rust dev btw)