Migrate tracking APIs to DTOs

[MajorTanya]

Changes the handling of tracker API responses to be parsed to DTOs instead of doing so "manually" by use of jsonPrimitives and/or Json.decodeFromString invocations.

This greatly simplifies the API response handling.

Renamed constants to SCREAMING_SNAKE_CASE.

Largely tried to name the DTOs in a uniform pattern, with the tracker's (short) name at the beginning of file and data class names (ALOAuth instead of OAuth, etc).

With these changes, no area of the code base should be using jsonPrimitive and/or Json.decodeFromString anymore.