[Maps] Ability to configure index settings when importing geospatial files

[florent-leborgne]

Version: 9.2
PR: elastic/kibana#232308

This feature is especially to allow creating lookup indices on upload (by specifying the "index.mode": "lookup" index setting)

[nreese]

Chatted with @alaudazzi offline. Below is the summary of that conversation.

• Change is very minor enhancement and is not worth calling out in existing documentation
• Would be worth mentioning in the 9.2 release notes. Something like "Added 'index settings' to geospatial file import. Use 'Index settings' to customize Elastic index settings when uploading geospatial files."
• At some point in the future, it would be good to add an ESQL example to maps tutorials. This example should demonstrate the feature and show how users can upload regions with geospatial import, configure index settings by setting index:mode: lookup, and finally use ESQL and lookup joins to create region maps.

[alaudazzi]

Closing in favor of a note in the Release notes for 9.2.