Agents now report how a connection was made and which app made it, so
the connection log records the method and the client app separately.
- Bump the Agent API to v2.13. `Connection` gains `connection_method`
and `app_name`, and `type` is deprecated.
- SSH and reconnecting PTY handlers set the method themselves, so a
client-supplied app name can't change it.
- SSH sessions report the app from `CODER_SSH_SESSION_TYPE`. Sessions
without one count as SSH but report no app.
- Disconnect reports repeat the connect report's method, app, and
client session ID.
- Coderd logs the reported method and normalized app name. For agents
older than v2.13, it maps `type` as before.
- Coderd rejects unknown methods instead of logging them as SSH.
Closes CLIENT-1037
Ehab Younes
f573ec3533