Undo tree display / navigation

[haasn]

Check for existing issues

• Completed

Describe the feature

A very popular (and useful) feature among editors is the ability to maintain, display, and navigate an undo tree. This way you can e.g.:

• Quickly view a previous version of the buffer you're editing
• Make changes after undoing a (sequence of) commands without losing progress
• Inspect your history of saved versions and quickly navigate between older variants (e.g. for testing)
• Easily go back to the latest version of a buffer after a sequence of undo commands

And definitely more. In general, it gives us a way to track changes on a level of granularity too fine for e.g. git commits to sensibly track.

If applicable, add mockups / screenshots to help present your vision of the feature

Vim's undotree plugin can offer some inspiration:

(Observe also the fantastic utility here of having #15097)

[aeshna-cyanea]

for reference (to show that there is demand), here is an equivalent issue in vscode microsoft/vscode#20889