Sqlite Collation Support

[agentsim]

Adds a method create_collation to SqliteConnection.
Adds a unit test confirming the collation works as expected.

[agentsim]

Per the comments in #430, this adds the method directly on SqliteConnection.
The implementation is essentially a direct copy of what rusqlite did. I put the method in a separate module, collation, that seemed to be similar to the approach taken with other methods on SqliteConnection.

I had some trouble with the unit test, I'm not sure the why I coded it is best.

[agentsim]

@mehcode @abonander I think this is ready to be merged. The CI failures appear to come from existing code in the master branch.

[mehcode]

👍 Thanks for seeing this through

[jeremymarch]

Is it possible to create a collation for a Sqlite Pool? Or only a single connection?

[abonander]

In the version we just released this week, you can configure collations on SqliteConnectOptions which when used with a pool will create those collations on all connections created by the pool: https://docs.rs/sqlx/latest/sqlx/sqlite/struct.SqliteConnectOptions.html#method.collation

[jeremymarch]

Perfect! Thanks so much!