Request bodies can be streamed or partially read

Request bodies can be read entirely into the internal request buffer, or converted into a RequestBodyReader, which implements Read.

Closes sammhicks#21

Merge branch 'fix-newline-in-websocketkeyheadermissing' into main

Added embassy support and shutting down sockets

Added support for embassy Timers
The socket is now shut down after it has finished handling requests

Using const_sha from crates.io as it now has no_std support

Config::new is const

closes sammhicks#18

Only automatically send the "Connection" header if it has not already…

… been sent by the handler

Allows configuration of behaviour after response has been sent

Using stable Rust 1.75

Fixed Serializing empty structures to JSON

Closes sammhicks#11

Improved semantics of query and form parsing