Make MyRespiLens data conversion happen in the drag-n-drop (js rather than python pipeline)

[emprzy]

Longterm wishlist item:

Make it s.t. drag-n-dropping a Hubverse-style .csv file into MyRespiLens will automatically convert it to the RespiLens projections-style JSON (so that users don't have to locally run the conversion script).

This will require me to re-write the Python/R logic of external_to_projections in JavaScript code. A bit of an undertaking b/c I'm much less familiar with js code, but this will make MyRespiLens much more professional and user-friendly.

[emprzy]

Note that our external_to_projections.py script presently only handles a single file at a time. let's transition it to handle a directory/multiple files at a time and then potentially run the script through MyRespiLens. It also does not handle any pathogen other than covid, flu, RSV. This is another thing we should think about changing (but secondary to the former).

[emprzy]

Need to make MyRespiLens compatible with multiple locations and potentially targets as well in order to support this. Also note that MyRespiLens doesn't have an advanced control panel when perhaps it should. MyRespiLens needs. major updates if we are going to proceed with the site