feat(py): Expose Expr.matches to Python

[alukach]

This PR exposes the Expr.matches functionality to Python.

When writing tests, I was arguably a bit heavy handed by way of:

1. Reworking imports slightly as I found it odd that we were importing the entirety of the cql2 module and then some specific classes despite already having access to them from the module
2. Adding a parameterized test, which doesn't seem to be used in this project

Feel free to push back on style or scope of changes, I was very much stumbling my way through this.

[gadomski]

Reworking imports slightly as I found it odd that we were importing the entirety of the cql2 module and then some specific classes despite already having access to them from the module

This is a me thing, I like to import classes directly but use functions w/ a namespace — habit from somewhere, don't remember where. Totally fine w/ your rework.