Allow cross DevWorkspace volumes

[sleshchenko]

Description

It's supposed that there are several cases when using cross DevWorkspace volumes can be useful for optimization, like:

• cache extensions Avoid re-downloading the same extension again and again eclipse-che/che#20592
• cache artifacts repos (maven, go, node)

It may somehow be possible to archive with labeling PVC but I believe it supports only one volume mount path.

Unclear aspect:

• user would needed to be aware of that fact and manually clean up cache to avoid exceeding PVC size;
• at which level it should be defined? devfile? devworkspace? is it Che who reclaim user's volume to be cross namespace... Should be make all volumes cross deworkspaces be default and only scope projects? something else?

[sleshchenko]

duplicates #630