Support compound che tasks

[RomanNikitenko]

Is your enhancement related to a problem? Please describe.

Recently theia started to support compound tasks.
Please see https://code.visualstudio.com/docs/editor/tasks#_compound-tasks for more details.

I tested the corresponding PR to theia project to investigate the influence on che tasks.
So, for example, if you have some build task which depends on subTask_1 and subTask_2:

• subTask_1 is started
• subTask_1 is completed
• subTask_2 is started
• subTask_2 is completed
• the task build is started

Also user has ability to define order for sub tasks: sequence or parallel

Please see a short demo for the current state of che tasks: https://youtu.be/zhHkAunnAp0

Looks like in general it works for che tasks, but some adaptation is required on che-theia side

Describe the solution you'd like

We need at least:

• add the corresponding fields to the che task schema to get working the content assistant for new fields
• update the documentation for che tasks
• at the moment compound tasks work from Terminal => Run Task menu, but don't work from Workspace panel

[che-bot]

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[che-bot]

Issues go stale after 180 days of inactivity. lifecycle/stale issues rot after an additional 7 days of inactivity and eventually close.

Mark the issue as fresh with /remove-lifecycle stale in a new comment.

If this issue is safe to close now please do so.

Moderators: Add lifecycle/frozen label to avoid stale mode.