Add context method to request context

[987Nabil]

@jdegoes rfc

[guersam]

It seems like a DX improvement with a function that can replace ZIO.service[A] with a shorthand, revealing the intention more clearly. Nice to see this addition!

My two cents: context tends to be used much more frequently in user land code than handler, so exposing zio.http.context via import zio.http.* might cause unwanted shadowing. I'd prefer useContext or withContext.

[jdegoes]

@987Nabil Looks good! Maybe we can call the function withContext instead of context? Matches the name of the type class too.

[987Nabil]

@jdegoes done