Investigate Support for multi-root workspaces with PHP plugins

[tsmaeder]

We need to investigate how our PHP support works with multi-root workspaces. In particular, what happens when we start with an empty workspace, then "add folder to workspace", then add a second workspace root.

[tsmaeder]

Also, inspecting the code would be a good idea.

[tsmaeder]

Steps to test would be:

1. Create an empty workspace in Theia (I know how, it's simple)
2. Add a php project as a workspace root
3. Ensure language features (code assist, etc.) work (filing issues for stuff that does not)
4. Add a second project as a workspace root
5. Test language features work

[vrubezhny]

I've tested the multi-root workspace support with PHP Intelephense, using v.1.0.13 of the extension by setting the value workspace.supportMultiRootWorkspace preference to true and going through the following the steps: #14225 (comment)

For all the projects added by Add Folder to Workspace command I was able to see the hovers, invoke content assistant and edit the contents of the php-sources in every added project.

open terminals for each of the projects as well as for the initially opened folder.

Also I've followed the list of requirements described in eclipse-theia/theia#1660. The most of them are seem to be met (those I could spot visually while working with projects), like:

• Search shows the results for all the projects with occurrences, separating the results by project roots.
• Workspace name is displayed at the header of the Project Explorer
• A previously saved (into a *.theia-workspace file) can be opened with Open Workspace command.
• Open Terminal command suggests to open a terminal view from the list consisting of the workspace folder as well as the every project-root folder added to the workspace.
• When making Drag&Drop on a folder between two projects in a milti-root workspace, the folder gets moved into a destination project and removed from the target project. LS is functional on the files of the moved folder.
• Editor filename tooltip as well as Project explorer filename tooltip shows the full filename.

[tsmaeder]

@vrubezhny what about document symbols and hover, as mentioned in #13427 (comment) ?

[JPinkney]

@tsmaeder I think it was actually my misunderstanding of PHP for those issues. I believe everything is working as expected as documented in eclipse-che/che-theia#408.

The PHP plugin doesn't show document symbols and hover for super basic elements like echo "Hello World" but when you actually make a PHP class everything was working as expected (I found this out after that comment was posted)