src: use itty-router for routing requests

[flakey5]

Closes #122
Closes #106
Closes #111

TODO

• r2 middleware
• origin middleware
• caching middleware
• tests
• commenting
• custom request type (contains parsed url so we only do it once)

[flakey5]

cc @ovflowd

[ovflowd]

Partial review! Going to review more later :)

[ovflowd]

Shouldnt these be handled by itty router why path regular expressions? Ie:

/some/path/{something}/some/other/matcher

[flakey5]

We are handling parts of the path with itty router here, but that just pulls out some info from the path so that we can use it later.

We still need to take the relevant parts and make the path in the r2 bucket, which is what this function does

[ovflowd]

Can't we use itty router again for that? Like a layered strategy?

So an in-router router? Because that is the part I really wish to become "easy to handle" by just using itty-router

[flakey5]

Maybe? I'm not really sure what that would look like

I think with this approach we're still better off though. It's still a tiny bit messy but a lot more understandable than what we have now and would probably be simpler than having an in-router router imo

I also debated doing something like

router.get('/:rootPath/?:path+', [cached(r2Middleware), originMiddleware]);

that way we can just use a switch statement in getR2Path, which might help with cleaning it up. Performance wise it should be about the same. Might cause some annoyances if we want to add other GET paths to the worker later down the road though

[flakey5]

should build still be on the codeowners for this file?