Pass request header parser through factory

[christoph-kluge]

Split-off from #217 and extension to #40. This PR adds the ability to pass a custom RequestHeaderParser to the server.

• Adds option to pass a RequestHeaderParserFactoryInterface (someone up for a shorter name?)
• If none is passed, we take the default one shipped by the server
• If one is passed, it's taking the custom one

As soon as #241 gets merged we could also extend this factory with a custom parameter to enrich the RequestHeaderParser with for a custom maxSize. This could then complete #214.

[clue]

Thanks for filing this PR! I like the direction this is heading, however I do not think that a factory pattern makes much sense here. As an alternative, I would suggest making sure the RequestHeaderParser is no longer stateful and can be re-used for any number of requests. What do you think about this?

[christoph-kluge]

I think I would change from the factory to an RequestHeaderParserInterface instead of a concrete. As you suggest it makes sense to have the RequestHeaderParser stateless. I think will follow the PSR7-MessageInterface and implement some kind of withConnection() (or similar) which will return a cloned instance of the RequestHeaderParser to achieve immutability and stateless usage. What do you think of it @clue ?

[WyriHaximus]

Moved this to v0.8.2 as we haven't heard back from you. Are there any updates?

[christoph-kluge]

@WyriHaximus waiting for @clue's feedback before I touch it again.