Implement reversion of nodes after editing via searcher.

[MichaelMauderer]

Pull Request Description

Add functionality to revert a node that was changed during editing through the searcher. Note that currently, nodes are not edited by the searcher, except upon confirmation, Thus this functionality results in a no-op at the moment.

Important Notes

[ci no changelog needed]

Checklist

Please include the following checklist in your PR:

• [x] The documentation has been updated if necessary.
• [x] All code conforms to the Scala, Java, and Rust style guides.
• All code has been tested:
  • [x] Unit tests have been written where possible.
  • [x] If GUI codebase was changed: Enso GUI was tested when built using BOTH ./run ide dist and ./run ide watch.

[MichaelMauderer]

Actually, as I've checked the aborting editing... do not revert the expression at the moment. I think this is a regression. So we actually can check if this branch fixes it.

After checking, it appears that this is not fixed by this PR at the moment. Only the source code is reverted, the view logic was not changed and seems not to revert right away, only after some other update triggers a re-evaluation of the view expression.

[MichaelMauderer]

Actually, as I've checked the aborting editing... do not revert the expression at the moment. I think this is a regression. So we actually can check if this branch fixes it.

After checking, it appears that this is not fixed by this PR at the moment. Only the source code is reverted, the view logic was not changed and seems not to revert right away, only after some other update triggers a re-evaluation of the view expression.

The tracking issue is filed here: https://www.pivotaltracker.com/story/show/182926584 This should be fixed in a later stage of the user story that reworks some of the related functionality.

Aborting editing via `Esc` does not correctly update node view - Pivotal Tracker