Create numbered and bulleted lists

This PR aims to add the creation of lists in a document. This only aims to support numbered and bulleted lists and not image bullet lists for now.

# TODO
* [x] Editor UI buttons
* [x] Detect list style at selection
* [x] Ops for list insertion/removal
* [x] OT support
* [x] Convert selected text to a list or selected list back to text
* [x] Add feature flags and session constraints
* [x] Default styles for numbered and bulleted lists

Seems we misunderstood each other :) I only asked for removing the API documentation of this flag `listEditingEnabled`. The mechanism to have `listEditingEnabled` only enabled if also `unstableFeaturesEnabled` is set I was fine with. Because it would allow us developers (and curious users) to enable, but protect innocent users from accidentally enabling it.