New control - Maps and also adding "ExtensionContext" to PeoplePicker and List Cntrol

[anoopt]

Q	A
Bug fix?	[ ]
New feature?	[X ]
New sample?	[X ]
Related issues?	NA

What's in this Pull Request?

1. Added a new control called "Maps" as a response to New control: Map control #14

The current version of the submitted PR, accepts co-ordinates (latitude and longitude) as properties and displays OpenStreetMap for the co-ordinates.
The plan is to add "city search" in the upcoming weeks and use Google's geocode service to get co-ordinates for the entered city. This will need API key (which is free only for some queries and after that would need billing enabled for premium services).

2. Added "ExtensionContext" reference in ListPicker and PeoplePicker controls.

There are times when we would need to use these controls in SPFx extensions as well. Hence I have added the reference to "ExtensionContext" in these controls and the context in these controls can now be of the type "WebPartContext" or "ExtensionContext".

context: WebPartContext | ExtensionContext;

Sharing is caring

[anoopt]

Adding more changes - hence closing this PR.

[AJIXuMuK]

It’s not necessary to close the PR if you want to make more changes. Just add commits to the branch and push them. All the commits will be automatically added to the PR.
From other hand, to my mind, it’s better to have separate PR for different functionality.
In current situation I would create one PR fir ExtensionContext and another for Map control.

[anoopt]

Thank you Alex for the suggestion.