WebIDE show fork button when cannot push code

What does this MR do?

This MR closes #213581 (closed) by adding the "Fork project" or "Go to fork" button when the user cannot push code and opens the Web IDE.

Screenshots (strongly suggested)

UPDATE:

Fixed the alerts showing up during the forking 🎉

User open IDE and can fork
20210318_ide_fork_project_no_notice

ORIGINAL:

User opens IDE and can fork	User opens IDE and has fork
20210314_demo_ide_fork_new	20210314_demo_ide_fork_existing

User opens IDE and can push code (no alert)

Does this MR meet the acceptance criteria?

Conformity

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• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

References

Related to #213581 (closed)