WIP Make Che use multi root workspaces by default

[JPinkney]

What does this PR do?

This PR makes Che use multi root workspaces by default.

It is still WIP because there are underlying issues with the vscode-languageclient-node library that causes a race condition between when a project is cloned and when the didUpdateWorkspaceFolders is enabled. See: microsoft/vscode-languageserver-node#451

Related issues for C# and PHP support:
eclipse-che/che#14223
eclipse-che/che#14225

This PR will be considered mergable when the vscode-languageserver-node fix is in and all the stacks are behaving as expected.

Currently, this is status of the stacks:

Stack	First project works	Second project works	Issues/Comments
Java-maven	🚫	🚫	still same classpath issue
Golang	👍	👍	everything is working as expected
PHP	👍	👍	everything is working as expected
PHP Symphony	👍	👍	everything is working as expected
Python (without clicking "Try it now" in the popup)	👍	👍	everything is working as expected
Python (after clicking "Try it now" in the popup)	⚠️	🚫	Document symbols, hover, format, autocompletion worked on the first project. Validation did not. On second project import I have to re-click "Try it now" and then it says a process is now listening on port 2503
NodeJS React	👍	👍	everything is working as expected
.NET Core	🚫	🚫	No features are working with first project or second project.

Testing involved using the sample and adding in:

  - type: cheEditor
    reference: >-
      https://gist.githubusercontent.com/JPinkney/fd653195c71604e3b3002e46393b0f18/raw/1240df21746c56ac4ff66ecd8ee3a9767b074e68/reference.yaml

as the cheEditor in the devfile. That referenced yaml is the result of building a che-theia image with these changes.

Then I waited for clone to finish, tested out features. Then added in a second project (either by cloning or by creating a new folder in /projects) and tested the features on that. For Golang, Python and NodeJS React I just made new sample project myself inside of the /projects folder and added them to the workspace. For PHP I cloned https://github.com/banago/simple-php-website.

What issues does this PR fix or reference?

Part of the fixes for eclipse-che/che#13427

Release Notes

Docs PR

[che-bot]

Can one of the admins verify this patch?

[dmytro-ndp]

crw-ci-test

[che-bot]

E2E Happy path tests of Eclipse Che Single User on K8S (minikube v1.1.1) has failed:

• build details
• "che-theia" docker image: maxura/che-theia:408
• test artifacts
• https://github.com/orgs/eclipse/teams/eclipse-che-qa please check this report.
  Use command "crw-ci-test" to rerun the test.

[sunix]

cloneCommand.execute ?

[sunix]

I am not in favor of having logic implementations here. It should go to the command implementation.

[sunix]

i don't see any good reasons to rename execute to clone.
This is a command. At the moment we tell Che-theia to clone (running clone commands) at start up but we may chain other commands that are not about cloning.

[sunix]

same comments i had for factory-initializer

I am not in favor of having logic implementations here. It should go to the command implementation.

You see here you are duplicating code.
Also, workspace root folders may be handle differently in the future see: eclipse-che/che#15347

[benoitf]

currently superseed by #778
archiving