Add SerialProxyTap, a protocol-agnostic observer interface that lets a
companion component watch the bytes flowing through a proxied port and
inject bytes of its own (protocol acknowledgements, for example) without
owning the port. The tap machinery is compiled in only when a tap
component defines USE_SERIAL_PROXY_TAP, so ports without one pay nothing.
Add a per-port mode (RAW or PROTOCOL) with a matching API message so
clients control whether the tap is active. The mode belongs to the client
session: it resets to RAW whenever the subscriber disconnects, and RAW is
guaranteed inert so a client can flash firmware through the port without
protocol bytes being injected. Bumps the API minor version to 17.
Co-Authored-By: puddly <32534428+puddly@users.noreply.github.com>
Co-authored-by: J. Nick Koston <nick@koston.org>
Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>
Co-authored-by: J. Nick Koston <nick@home-assistant.io>
