Add "Map Control - Geocoder" to the Leaflet

I'm not perfect, but it's working. I tried to keep the design pattern.

I used an external library to do the geocoding and could not use the google maps geocoder already available in the module. Should I make a custom google geocoder adapted to the leaflet?

Even though you have not yet approved my previous patch, I've added a adapted geocoder google.

Hey, this is wonderful, but it has some issues:
- Do not write es6. It needs transpiling to es to be used with Drupal and I do not want to to that yet
- The google geocoder should work. The TOC from Google technically do not allow to use it with OSM, but that is seomthing others can decide
- In return, Nominatim and Photon should be available for other usecases as well. Their TOC do not forbid that
- I recently added a very simple Nominatim Geocoder. They need to be merged. Yours is more sophisticated
- I reworked some parts of the geocoder handling. Code needs to be adapted to that.

- Clean up a lot of the geocoding stuff and unify it
- add Photon geocoder

Thanks @Tomazetti. I rewrote a lot of the code, but it's still based on yours.

Glad to help. Great job with the module, it's great to have an active maintainer.

I'm testing the geocoders and I found some problems. Should I describe them here or create another issue?

And one question, the google geocoder gets the API address formatted and displayed in the suggestions, but the photon API does not provide the formatted address. Do you think it would be interesting to format the address to display in the suggestions?

- new issues please
- if you want to add the magic to print a formatted address, you are very welcome to do so
- the photon geocoder also has a weighted location setting. You could add the settings for that, seems useful

I would add single issues for each.

Thanks a lot!