Print more understandable messages on error:
- When ps fails because the monitor doesn't attach to any session, print "no
attaching session" instead of "unknown ref".
- Avoid disconnect silently fails when the monitor doesn't attach to any
session. Print "no attaching session" error instead.
- Fix error message of "attach"'s arguments. ("server name must be passed" ->
"ID of session or process must be passed")
Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>
This commit moves monitor commands to `monior/commands` package.
Commands still need access to the `monitor` object and buildx controller so this
commit enables this via `Monitor` interface stored in `monitor/types`.
Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>
