[roll] Roll fuchsia [fidl][cpp] Move function bodies & asserts out of wire_types.h

This move all static_asserts and almost all function bodies out of
generated wire_types.h files. This means that they're only evaluated and
compiled once per build (modulo toolchain, subbuild, etc). Because these
headers are very widely included this has an impact on the build time
for many compilation units. The remaining function bodies are just some
templated functions and helpers to convince the compiler to resolve
types in the right order.

Locally I was comparing the build time for sdk/lib/zxio/debuglog.cc
because it's a pretty small, simple file that was taking a long time.
The compile time for it (measured with hyperfine) dropped from 6.6s to
5.2s. Across the two CLs like this that's a reduciton from 10.2s to
5.2s.

There are still more optimizations to be done across other generated
headers.

Original-Bug: 361634289

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1255849
Size-Review: John Wittrock <wittrock@google.com>
Original-Revision: 0ecf136d4e05041dc370e93d88edc66d6ae8d0d0
GitOrigin-RevId: dc30c27e7dd338fab1d146fb7e81cc843dce4095
Change-Id: I3a5b087e893bd4f18bca1a45a3a25c2ee4d797a0