[roll] Roll fuchsia [bt][sapphire-rpc-macro] Drop server-only lifetimes

An #[rpc] impl block may borrow state that only the server uses, e.g.
impl<'a> Service for Handler<'a>. Such lifetimes used to leak into the
generated request, response, RPC and client types, so every client had
to name a lifetime it has nothing to do with.

The generated types now keep only the impl lifetimes that an endpoint
signature, a type or const parameter bound, or a where clause
mentions. The generated route_request function is also made public so
a server loop defined outside the impl's module can dispatch requests.

Test: fx test sapphire_rpc_macro_test
Original-Original-Bug: 552502495
Original-Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1854656
Original-Original-Revision: 49c306b6df51ba743937b7c12bca7600020a1053
GitOrigin-RevId: 2d0a90bf9b77088d52cf5f8c3a28823f057d5519
Change-Id: I14478dda0f3c15c9d08fa5009ced535860aa6914
Reviewed-on: https://fuchsia-review.googlesource.com/c/integration/+/1855278
Cr-Commit-Position: refs/heads/main@{#203696}