fix: enable API requests on Flutter side

[samirakhmedov]

What is the new or updated feature that you are suggesting?

Change the way of passing Mapkit API key.

Why should this feature be included?

A lot of features from Mapkit could be enabled, if the Mapkit API key was enabled on the Flutter side. However, it is only on native side, so there is no way now to implement calls to API.

What could be enabled with the API key on the Flutter side:

• Organization search
• Geocoder and geosuggest
• Locator API (probably)
• Distance matrix API
• Routing details API