Add content locking (anti-concurrent editing) to core?

Problem/Motivation

• Views UI implements locking to prevent two people from concurrently editing the same View.
• The node edit form does not implement locking. In other words, two people can be filling out the same node's edit form at the same time, the first person to save "wins", and the second person gets a validation error when they try to save (after they've already done a bunch of work filling out the form).
• #3025231: Concurrent editing of layouts is very confusing is proposing to add locking (similar to Views UI) to Layout Builder.
• The result of the above would mean that the Edit tab of a node would continue to not implement locking, while the Layout tab would. That seems potentially confusing.

Proposed resolution

• Decide whether we should add content locking to core. There's prior art for this in https://www.drupal.org/project/content_lock.
• If we decide not to, then discuss whether we're concerned about the difference in behavior between the Edit tab and the Layout tab, and what to do about it.

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet