Addition of location share feature (#3924)

* added new mapview package, added code to handle location share button

* added rocketchat:mapview to active packages

* updates to MapView package to support google static maps

* updated link target to blank page

* changed location button to depend on settings

* corrected eslint, changed var names

* updates to settings code

* changed maps link to navigate link for android+ios support

* stripped trailing spaces

* moved mapview files into subfolders under package

* added focus event back to location button

* add i18n entries to en file, update settings with i18n keys

* add modal confirmation of location share, moved location to geojson property under the Message model

* https://docs.mongodb.com/manual/core/2dsphere/ -> 2dsphere indexes are sparse by default and ignores the sparse: true option.

* button depends on location API being available. Tested in Chrome, Chrome Mobile, and Cordova Rocket.Chat from Store.