Enable users to select custom vector map for visualization

[Shivamdhar]

Description

In case custom maps are uploaded by the user, the layer options tab provides a choice for users to either select default or custom map for visualization. The PR adds logic for custom map selection and projection via leaflet.

Fig. showing choice of selection between custom and default vector maps (in case custom map is uploaded by user)

Fig. showing us counties visualized on base map (based on custom vector map selected)

Issues Resolved

#1408
Task - Allow users to select index as custom vector map for visualization

Check List

• New functionality includes testing. (more tests will be added)
  • All tests pass
    • yarn test:jest
    • yarn test:jest_integration
    • yarn test:ftr
• New functionality has been documented.
• Commits are signed per the DCO using --signoff

[codecov-commenter]

Codecov Report

Merging #1718 (903125f) into main (4e117c3) will decrease coverage by 0.00%.
The diff coverage is 57.69%.

@@            Coverage Diff             @@
##             main    #1718      +/-   ##
==========================================
- Coverage   67.52%   67.51%   -0.01%     
==========================================
  Files        3067     3073       +6     
  Lines       58973    59067      +94     
  Branches     8944     8961      +17     
==========================================
+ Hits        39822    39880      +58     
- Misses      16972    17004      +32     
- Partials     2179     2183       +4     

Impacted Files	Coverage Δ
src/plugins/region_map/public/region_map_fn.js	100.00% <ø> (ø)
...gion_map/public/components/default_map_options.tsx	50.00% <50.00%> (ø)
...egion_map/public/components/map_choice_options.tsx	53.33% <53.33%> (ø)
src/plugins/region_map/common/constants/shared.ts	100.00% <100.00%> (ø)
...egion_map/public/components/region_map_options.tsx	100.00% <100.00%> (ø)
...ins/region_map/public/components/style_options.tsx	100.00% <100.00%> (ø)
...aps_legacy/public/common/opensearch_maps_client.js	0.00% <0.00%> (ø)
...plugins/maps_legacy/public/map/service_settings.js	1.62% <0.00%> (+0.72%)	⬆️
... and 2 more

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[ashwin-pc]

Can we also add some tests for all the new code introduced?

[ashwin-pc]

Thanks Shivam! LGTM

[ashwin-pc]

nit: since most of the fields here remain the same across the tests, you can set a default one and only override the props you need to be different for each test so that reading the tests is a lot easier.

e.g.

const DEFAULT = {
      colorSchema: {},
      outlineWeight: {},
      ...
}

// And in test 1

const viz = {
    ...DEFAULT,
    ...{
        customProp: something
    }
}

The same comment goes for the other tests too.

[VijayanB]

LGTM!