Move passes out of rewrite folder

[johnzl-777]

Currently to access some of the bloqade passes you usually have to import them via:

from bloqade.rewrite.passes import AggressiveUnroll

This seems to go against the current convention which is that you have two separate folders, one for the actual rewrite rules and another for the passes that are composed of those rewrite rules.

Then you end up with an import that looks like:

from bloqade.passes import ...