[Maps] layer groups

[nreese]

Fixes #37252

PR enhances Map legend, allowing users to group layers into tree view. PR updates remove layer action with a modal ensuring users are aware that removing a layer group will also remove all sub layers.

Create layer group

Click the grab handle to the right of layer in the legend and hold the mouse button to initiate dragging. Then, drag the layer until it over laps with another layer. The layer will become semi-transparent and the mouse cursor will change to indicate when in "combining" state. Let go of the mouse button and a new layer group will be created that contains the 2 layers.

Move layer group

Layer groups can be re-ordered like any layer by dragging the "reorder" handle in the legend. Re-ordering a layer group will also move all sublayers to new tree location. Layer groups cannot be moved into their ancestry chain.

Move a layer into a layer group

There are 2 ways to move a layer into a layer group. Do one of the following:

• drag layer onto layer group entry until layer is semi-transparent and the mouse cursor will change to indicate when in "combining" state. Release mouse button. This will add layer to top of layer group
• drag layer in between layer group and layers contained by layer group. This will add layer to the layer group at the position of drag.

Move a layer out of a layer group

• drag layer onto layer group entry until layer is semi-transparent and the mouse cursor will change to indicate when in "combining" state. Release mouse button. This will add layer to top of layer group
• Use drag action to drag layer above or below layer group.

Follow up work

This PR is getting very large, so the following items have been excluded to follow up PRs

• Layer group telemetry - ui counter update showing how many maps user layer groups
• Layer group filter support - allow users to specify filter to layer group that gets applied to all sub layers of group
• Security map updates - use layer groups to organize client and server layers, [Maps] "Point to Point" Data Source #41575 (comment)

[nreese]

@elasticmachine merge upstream

[nickpeihl]

lgtm!

code review and tested in chrome

[nreese]

@elasticmachine merge upstream

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: 1d624bd

Metrics [docs]

Module Count

Fewer modules leads to a faster build time

id	before	after	diff
maps	1004	1008	+4

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
maps	2.7MB	2.7MB	+12.1KB

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
maps	82.1KB	82.1KB	+28.0B

History

• 💚 Build #79636 succeeded 1c1cfdb
• 💚 Build #79606 succeeded cd1447c
• 💚 Build #79429 succeeded 3acd081
• 💚 Build #79195 succeeded 4519cd9
• 💚 Build #79178 succeeded 99c3450
• 💔 Build #78877 failed d5901d9

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

[nreese]

@mdefazio let me know if you have any more feedback. We plan on refining the UI with follow up PRs.

[gchaps]

Text LGTM

[mdefazio]

I think this looks good. Happy to help in some follow-up PRs to add in some UI details to improve this, but I don't think these are blockers.

[elasticmachine]

Pinging @elastic/kibana-presentation (Team:Presentation)