Automatically batch style updates

[mourner]

Closes #2343. Removes map.batch and implements automatic batching of style changes, applying them once per frame. The style keeps track of all mutations done through Style setLayoutProperty, addLayer, etc., and then all mutations are applied with the style.update method which is called in map._render and happens once per frame.

Remaining tasks:

• fix API accessor methods to immediately reflect style changes before they're batch-updated, as per they do already remove map.batch and automatically batch style changes #2343 (comment)
• figure out why sprites-pattern render tests failed
• renames for clarity as suggested in Automatically batch style updates #2355 (comment)
• update examples, make sure they all work properly
• 👀 @jfirebaugh @lucaswoj @ansis @scothis and subsequent clean up

[lucaswoj]

The terminology here is starting to feel overwhelming: mutate, update, change, cascade, recalculate...

How do you feel about picking a consistent verb (i.e. update, change) and differentiating these properties and methods with direct objects?

• cascade -> updateTransitions
• recalculate -> updateZoom
• mutations -> updates
• broadcastLayers -> updateWorkerLayers
• reloadSource -> updateSource
• change event -> update

[mourner]

Yes, great point! I like all the suggested renames except the change event, which we use throughout the code for other classes, and it's generally more common to have events like this called change rather than update in JS APIs.

[mourner]

I'd also leave reloadSource -> updateSource rename for another PR because it's tricky, potentially involving a lot of changes that are out of scope for this PR (e.g. it calls source.reload, which in turn calls pyramid.reload, but pyramid also has update method which is different, so you also have to rethink pyramid API).

[mourner]

I've renamed mutations, broadcastLayers and did some other minor cleanups/renames, but leaving the rest for future PRs (especially cascade and recalculate) so that it doesn't interfere with current DDS PRs, otherwise we would have a lot of conflicts to resolve.

[lucaswoj]

👍 I openend #2359

[lucaswoj]

_resetMutations --> _resetUpdates

[lucaswoj]

This is ready to 🚢 once you address the two minor comments above.

Great work! I love a negative line PR.