[Enhancement] Add pluginName=Keplergl url parameter to Mapbox API requests

[ryanbaumann]

Adds a URL parameter pluginName=Keplergl to all Mapbox API requests made from the mapboxgl.map object cc/ @heshan0131 @chrisirhc

Example transformed API request:

• Tiles: https://b.tiles.mapbox.com/v4/mapbox.mapbox-terrain-v2,mapbox.mapbox-streets-v7,eklimcz.00zz64mq/9/81/198.vector.pbf?pluginName=Keplergl&access_token=my-token
• Non-Mapbox API requests (requests not to api.mapbox.com or *.tiles.mapbox.com) remain unchanged

Known issue

When adding a custom Mapbox style, the map options for transformRequest are not maintained. Map options for transformRequest are maintained when selecting from the list of Kepler.gl styles muted light, light, etc.

@heshan0131 is the map initialization handled for custom Mapbox GL style sheets differently than Uber-sourced styles?

Tests are failing on Travis but pass locally running with yarn run test. Not sure why.

To Do:

• Determine why the transformRequest map options are not maintained when using a custom map style
• Fix tests

[chrisirhc]

Looks like it's lint errors:

[heshan0131]

let transformedUrl = url;

[heshan0131]

don't need this else statement here

[heshan0131]

What do you mean by not maintained?

[heshan0131]

I see what you mean now. You should also add the prop to
add-map-style-modal.js

[ryanbaumann]

Thanks, @heshan0131 for pointing me in the right direction! I added new props using the same format as in map-container.js into add-map-style-modal.js and confirmed that the URL parameter is added to Mapbox custom styles now. Let me know your final review.

Travis tests seem to be failing for an unrelated reason -- all lint and test commands pass locally. Here's the Travis log -- I'll try pushing again in a few hours and see if it reproduces.

[heshan0131]

travis build is fixed, rebase and it should work now

[ryanbaumann]

@heshan0131 thanks for the help with the NPM changes, all tests are passing now. Apologies for the slightly ugly rebase commits above - they are all duplicates of previous commits except for the last merge master into this branch change.

Ready to merge if you are. Tested on both custom Mapbox map styles, default map styles, and map styles with non-Mapbox-api resources.

[heshan0131]

@ryanbaumann, I updated the branch to only include your changes, also moved the code to a util