Feature Request: Multiple build-base and install-base for multiple base-paths

[tonynajjar]

It's possible to have multiple base-paths currently but it's not possible to have multiple build-base or install-base. I have 2 workspaces, one underlay and one overlay, and I would like to configure different build-base and install-base for them respectively. Something like:

{
  "build":
    {
      "symlink-install": true,
      "mixin": ["ccache", "release"],
      "base-paths":
        [
          "/home/tony/underlay_ws/src",
          "/home/tony/overlay_ws/src",
        ],
      "build-base": ["/home/tony/underlay_ws/build", "/home/tony/overlay_ws/build"] , # order would matter to match base-paths order
      "install-base": ["/home/tony/underlay_ws/install", "/home/tony/overlay_ws/install",
    },
}

We should also consider what this would mean for the mixins and potentially other arguments; are they applied to both workspaces or should we also be able to specifiy different mixins for different workspaces.