Multiroot workspace: project must appear in the project explorer when it was cloned by a command in terminal

[vitaliy-guliy]

Describe the bug

In the multiroot workspace projects only appear if they are described in the devfile.
If we create a simple workspace w/o projects and then open a terminal and clone any project by hands, this project will not be opened in the Exporer view.
The same we have when trying to clone a project by Git: clone command.

Workspace plugin handles adding of the project to the devfile when cloning them by hands.
It's a good candidate to handle file system changes and register newly cloned projects in /projects/che.theia-workspace

Che version

• nightly

Steps to reproduce

• Create workspace w/o projects

• Open terminal, clone any project with git clone ...

• Try to clone another project with Git: clone command from command palette.

• Check the file system. Open a terminal and run ls /projects

Screenshots

[RomanNikitenko]

duplicates #19101

[azatsarynnyy]

I'm transferring the labels from the original issue #19101 (comment)

Setting label new&noteworthy and milestone DevWorkspace Integration STEP 2 as it blocks #19489

fyi @l0rd