`devenv up` should attach to an existing process-compose server, if one exists

[austinried]

I'm not sure if this behavior is desired or not but I found it confusing that I could run devenv up multiple times and start multiple process-compose servers. If I run devenv up once and lose the shell for some reason, I now have a phantom process-compose server running in the background that I don't know how to interact with.

I think it would be smoother if a second devenv up/devenv processes up checked to see if there was an existing process-compose server already and attached to it instead. It seems that devenv processes attach exists, but it only works if you started with up -d first.

[domenkozar]

Yeah, that's a good idea!

[wgordon17]

devenv processes attach, is this a real command? I'm not seeing it on devenv 1.3.1 (aarch64-darwin)