[Maps] Improve new draw shape flow

[kindsun]

Following up on the introduction of the new layer wizard and layer edit tools, we need to tie together the user experience to create a better flow unifying the two tools. The following capabilities/changes should be introduced:

1. Update wording for new vector layer to indicate this will also entail drawing new shapes
2. Add some indication to layer TOC that the new layer (and any layer a user edits separately outside of this process) is in edit mode
3. Following new layer addition, show edit tools and indicate user should use them to add shapes to new index
4. Add exit drawing mode button to TOC

cc. @kmartastic @thomasneirynck

[elasticmachine]

Pinging @elastic/kibana-gis (Team:Geo)