Add support for table schema

[skytz]

What i did:

• added optional schema field for the ModelAttributes
• added optional schema_name for TableMetadata
• changed query statements to add schema (ex: from INSERT INTO \"{}\" ... to INSERT INTO {}\"{}\" ... where the first parameter is either empty string or "<schema_name>".

What's not done:

• add schema to the whole section related to joins
• add schema to the migration part of the code
• pass schema to sqlmo (i see it supports schema only that the functions used didn't expose that, i haven't gone too deep into it though)
• for sqlite, to bypass the schema (because it doesn't support it). It should be as easy as overriting the schema name to be None in TableMetadata, and everything should work.
• 🤷‍♂️ I'm sure i missed something
• tests with schema (current tests pass)

Would really appreciate a look over the code so far and maybe some help with this? 🙃

[kurtbuilds]

Love it. I'll review sometime this week.

[skytz]

I've made a pull request for sqlmo with the exposed schema fields and updated this repo to use that

I'll write some tests a bit later.

One thing thats really annoying is the formatting, i ran cargo fmt --all and its...a mess. I've made another pull request with only the formatting, and after you merge that, only the changes should show.

[kurtbuilds]

Thanks for these. I responded in the cargo fmt PR you opened. Hopefully that isn't a blocker for this contribution, as it's a welcome addition to the library.

[skytz]

I reverted the formatting. These should be the changes, and only the changes.