Add Google Hybrid, Esri Satellite, and HERE Hybrid base layers

[svet-b]

@amotl just wanted to submit this following your comment on grafana#210 (comment)

First of all, we massively appreciate your work and improvements on this plugin. They're nothing short of transformational in terms of its usefulness.

This PR adds three additional base layers, with a focus on satellite imagery. Namely Google Maps Hybrid, Esri Satellite, and HERE Hybrid. The default is set to Google Hybrid.

Note that merging this PR as it stands will straight up set the base layer to Google Hybrid - which may not be what people expect to see. In that respect, one major shortcoming is that there is still no UI selector for which base layer to actually use. At the moment this can be set manually by editing worldmap_ctrl.ts.

[amotl]

Dear @svet-b,

thank you so much for your contribution to this plugin and also thanks for your appreciation.

As @ryantxu was quick to pick up our work on this plugin, the codebase has been cleaned up thoroughly and diverged from the point you made this very pull request.

So, we are humbly asking if you could update your pull request accordingly if you find some time for that? Please note that the dist folder has been removed from the repository as it now contains solely the sources, which we consider to be a good thing.

Thanks already and with kind regards,
Andreas.

[amotl]

Dear @svet-b,

after grafana/grafana#20071 has been fixed, we are now able to bring quick turnaround times to new releases of this panel plugin, which we are currently publishing to [1]. They can be quickly installed like

grafana-cli --pluginUrl \
  https://packages.hiveeyes.org/grafana/grafana-worldmap-panel/grafana-map-panel-0.6.0.zip \
  plugins install grafana-map-panel

So, we will try to build fresh releases shortly after valuable contributions might be coming in [2].

Saying this, this might encourage you to give your PR a facelift in order to see it incorporated into a release package which will be able to be installed without any hassle on your Grafana instances.

With kind regards,
Andreas.

[1] https://packages.hiveeyes.org/grafana/
[2] #20