[Location sharing] - Pinned location

[mnaturel]

Your use case

What would you like to do?

Add the ability to share a location pinned on the map which will be different than the current user's location.

Why would you like to do it?

See https://www.figma.com/file/uthEK6xuo9hSQRdWvPAre5/Location-Sharing?node-id=365%3A141689
In short, the selected location will stay at the center of the map. User can select a location by moving the map to center the pin on a given location.
The share location view will update depending whether the selected location corresponds to the current location or not.

How would you like to achieve it?

Will use work done in #5395.

Have you considered any alternatives?

No response

Additional context

No response