Build daemon should support multiple different build scripts for the same project

[jakemac53]

Today if you have two build scripts and they are both ran in daemon mode, the 2nd one to launch will fail with an options skew error. It tries to use connect to the existing daemon for the project, which is running a different script.

We probably need the connect method to take an optional string identifier which would be appended to the workspace dir when creating the daemon identifier?

cc @grouma @jonahwilliams

I noticed this is breaking the current flutter web workflow when using the builders: key.