Resolution of scalajs:* files fails if the containing project aggregates another scalaJS project

[jmcclell]

When a project aggregates other projects, it runs the command sequentially on each of the aggregated projects and then finally on the specified project. However, in this mode, it adds a tab character to the start of each project's individual output. This means that the output for fastLinkJSOutput and fullLinkJSOutput have a tab character in front and the plugin doesn't trim it, so path resolution fails.

PR incoming.

[jmcclell]

If anyone else runs into this before this is merged, you can disable aggregation for this particular command in your project via:

Compile / fastLinkJSOutput / aggregate := false
and
Compile / fullLinkJSOutput / aggregate := false