Improvement of the ORM

[PenguinBoi12]

This PR is a major refactor of the Model and query system. It adds SQLModel, which is similar to our current Model, and includes a QueryBuilder on top of it to provide an API closer to Active Record or Eloquent.

Here's an example of grace's thread model:

# bot/models/extensions/thread.py
from grace.model import Model, Field, Column, Text, Integer


class Thread(Model):
    __tablename__ = 'threads'  # only needed because for old tables
    
    id: int | None = Field(default=None, primary_key=True)
    title: str
    content: str = Field(sa_type=Text)
    recurrence: Recurrence = Field(sa_column=Column(Integer))

thread = Thread.create(
    title="Daily Standup",
    content="Long content here...",
    recurrence=Recurrence.DAILY
)

daily_threads = Thread.where(Thread.recurrence == Recurrence.DAILY).all()
thread_by_id = Thread.find(1)

thread.recurrence = Recurrence.WEEKLY
thread.save()