Split parsing from validation completely

[RobbeSneyders]

During the refactoring for Connexion 3, we deduplicated all coerce_type calls during the refactoring and moved them into the uri_parser so it is done in a single place. When looking into #1931 however, I noticed we are still using the uri_parser from more places than we should.

This PR centralizes the parsing further into the ConnexionRequest class. During validation, we now instantiate a ConnexionRequest instead of a Starlette Request, and leverage it instead of calling the uri_parser directly.

I split the parsing and validation in the tests so they can be tested in isolation.

[coveralls]

coverage: 94.148% (-0.03%) from 94.179%
when pulling 576e67b on feature/split-parsing-validation
into 810a980 on main.

[Ruwann]

Nice, thanks!

[CordulaGuder]

Hi @RobbeSneyders, thanks a lot for looking into my PR and providing this change, which seems to make a lot of change! Trying it out, I found that it only applies to path and query params, and not to header params. Parameter validator gets request.headers, which, on further investigation, is not a property of ConnexionRequest, but only exposes the headers property of the underlying Starlette request object. On this, no type conversion is being done, so I'm now seeing the exact same issue as before.

Trying to fix this by adding a header_params property to ConnexionRequest, I stumbled over more issues. For some reason, I don't know whether that is a bug in Connexion or a misconfiguration on my side, the URIParser used in the ConnexionRequest doesn't have the param_defn from the API spec, so it skips the type conversion. I decided to stop the migration effort here for a while as it's been taking too much time already. This is just to inform you about the things I've noticed.