HttpClient configuration with modules

[tobrun]

WIP, alternative approach to #12423. This PR differs from #12423 as it doesn't expose a runtime configuration anymore. Providing an alternative httpclient is done at compile time. To support this kind of functionality, two new modules had to be introduced:

• MapboxGLAndroidHTTPBase
  • contains the definition of a HttpRequest + interface definition to communicate back to the sdk
• MapboxGLAndroidHTTP
  • depends on MapboxGLAndroidHTTPBase
  • contains an implementation of the HttpRequest using OkHttp.

How does providing an alternative http client look like for an user:

• user adds exclude module: 'MapboxGLAndroidHTTP' to their Mapbox SDK dependency declaration
• user provides an own implementation of HttpRequestImpl in a com.mapbox.mapboxsdk.http package (as example this is now done in the testapp using ion)

Benefits over #12423:

• we do not need to expose a static configuration, this results in not having to do additional bookkeeping of requests.
• we can use this integration in combination with current telemetry, we exclude the module that contains the okhttp libary but do not the exclude the okhttp library itself.

cc @mapbox/maps-android

[tobrun]

continuing this in #12468