Allow precise configuration of raw request body

[theseion]

The following body represents a chunk in a Transfer-Encoding: chunked request (content length, content, remaining chunks):

data: |
  7
  foo=bar
  0

While the contents of the lines is readable, the line breaks are not, but are relevant to the request, as the specification requires each line to be terminated with \r\n. In this particular context it is also not possible to properly encode the line breaks.

One idea to get around this limitation is to provide a "line specification", like so:

raw_lines:
  - content: 7
    ending: "\r\n"
  - content: "foo=bar"
    ending: "\r\n"
  - content: 0
    ending: "\r\n"

This format would give us more control and better readability, in addition to sending malformed request bodies.

[theseion]

We have encoded_request, that's good enough for now.