Add a loading icon/context for time-consuming processes, ie: geocoding providers, running adequacy analysis

[viviandien]

It's nice to have some feedback after a user has uploaded a list of providers.
I understand the geocoding of providers is not optimized currently, but it's helpful to understand that the application is working.

A few options:

1. make the application inactive. use a module overlay that shows a loading circle or bar with some text about what process is currently happening (geocoding, running time and distance analysis, etc)
2. put loading messages in respective drawers. ie: when geocoding providers, a loading circle or bar will show up in the Providers drawer (a user will have just uploaded a CSV here so this should make sense). then the map auto-zooms to encompass the new providers as well. (should be considered in Map auto-zoom and pan #12). when running the analysis, the charts/figures in the analysis drawer should be grayed out until complete.

[ericboucher]

Some good starting code can be found in
https://github.com/bayesimpact/tds/compare/guillaume-guillaume.f