[Live] Fixed idiomorph id child handling & JavaScript cleanup

[weaverryan]

Q	A
Bug fix?	yes
New feature?	yes
Issues	Fix #1470 Fix #1472
License	MIT

Hi!

TODO:

• Finish fixing minor js tests

Sorry, quite a lot going on here to get morphing & child rendering just right after switching to Idiomorph. The referenced tickets exposed a few cases that were not handled by the tests:

IMPORTANT CHANGES

• A) data-live-id is now id. That's because Idiomorph uses id as its special key. So it's time to embrace that.
• B) Fixed a bug if ChildComponentA were changed to ChildComponentB in the same location. Under some situations, we would NOT swap for the new HTML, and would instead "refresh" ChildComponentA.
• C) In the above situation, even when we DID swap to ChildComponentB correctly, the LiveController would still be attached to a Component object representing ChildComponentA. That would cause problems later on. We now watch for the id attribute to change, and then re-create a new Component if changed.
• D) Removed special "morph" handling for children components (which are always empty). Instead added a new data-live-preserve attribute for elements that want to keep their current element. Improved handling of this.

OTHER CHANGES

• Various internal attributes like data-live-emit were changed to Stimulus values, like data-events-to-emit-value. These are not attributes the user ever sets directly.
• Moved the remaining JS child handling into a plugin
• Added morph:started and morph:finished
• Simplified "child" handling. Previously we really tried to keep track of our children as they were attached / detached. Now, if we need to know our children, we loop over all components to find children.

Cheers!

[smnandre]

Wow that's some major changes :)

Every one of them make perfect sense and, as we said a few times already, "better change while still experimental" :)

Is this the perfect time to create our missing UPGRADE.md file ?