Rebased onto upstream main at 4487f7b, five commits past 0.9.0. That
brings async response body and trailer filters (every ProxyHttp impl
has to follow), parameterized downstream sessions, the owned HTTP test
origin, and TLS offload tasks that abort when dropped. Minor bump
because the filter signatures changed.

Signed-off-by: Shane Utt <shaneutt@linux.com>