Support for keyword arguments for `Request`/`Response`.

[ioquatix]

It can be tricky to specify positional arguments as Request (especially) and Response take several arguments, some of which are not always specified.

We introduce support for keyword arguments which makes it easier to read and write code which deals with complex request/response scenarios.

client.get("/index.html", headers: ..., authority: ...)

Types of Changes

• New feature.

Contribution

• [x] I added tests for my changes.
• [x] I tested my changes locally.
• [x] I agree to the Developer's Certificate of Origin 1.1.