In summary, this commit modifies 'Responder' so that:
* ..it is no longer 'async'. To accommodate, the 'sized_body' methods
in 'Response' and 'ResponseBuilder' are no longer 'async' and accept
an optional size directly. If none is supplied, Rocket will attempt
to compute the size, by seeking, before writing out the response.
The 'Body' type was also changed to differentiate between its sized
'Seek' and chunked body variants.
* ..'&Request' gains a lifetime: 'r, and the returned 'Response' is
parameterized by a new 'o: 'r. This allows responders to return
references from the request or those that live longer.
Also:
* Remove 'response::ResultFuture'.
* Re-export 'tokio' and 'futures' from the crate root.
* Make 'ResponseBuilder::sized_body()' and 'async fn'.
* Remove the 'Future' implementation for 'ResponseBuilder'.
* Add 'ResponseBuilder::finalize()' for finalizing the builder.
* body_string_wait and body_bytes_wait are removed; use `.await` instead
* `dispatch()` is now an async fn and must be .await-ed
* Add `#[rocket::async_test]` macro, similar in purpose to `tokio::test`
* Tests now use either `rocket::async_test(async { })` or
`#[rocket::async_test]` in order to `.await` the futures returned
from `dispatch()` and `body_{string,bytes}()`
* Update 'test.sh' to reflect the tests that should be passing.
Broken:
* Cloned dispatch and mut_dispatch() with a live previous response now both fail, due to a (partial) check for mutable aliasing in LocalRequest.
* Some tests are still failing and need example-specific changes.
Sergio Benitez
Jeb Rosen
Jacob Pratt