When fetched item is not a login, Bitwarden adapter raises NoMethodError
because the returned JSON does not have the login.password value.
Add a nicer error message for that case.
Avoid outputting this login error message, it wasn't an error and you
don't need to follow those instructions.
```
[ERROR] 2024/09/11 11:57:08 You are not currently signed in. Please run `op signin --help` for instructions
```
Rather than redirecting the global $stdout, which is not never clever in
a threaded program, we'll make the secrets commands aware they are
being inlined, so they return the value instead of printing it.
Additionally we no longer need to interrupt the parent process on error
as we've inlined the command - exit 1 is enough.
