feat: sdk 2095 remove models module from android v2

Ticket

Description

In this PR, we are dissolving the models module from the Android v2 project and the contents of this module, as well as the tests, which are moved in the android or core packages respectively, depending on the main logic of those.

We do that to minimise the number of supported modules that add further complexity, especially for a module that contains simple classes that don't provide any decoupling and could be better suited in other modules.

Also, by moving some core models in the core or android modules, we create a better ground for the test providers of the test classes in the respective modules.

Type of change

[x] Bug fix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds functionality)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
[ ] This change requires a documentation update

Implementation Details

Moved model classes regarding android module to android module
Moved model classes regarding core module to core
Fixed all package dependencies
Cleaned up and organised imports in most of the files
Cleaned up models module and deleted it

Checklist:

[ ] Version upgraded (project, README, gradle, podspec etc)
[x] My code follows the style guidelines of this project
[x] I have performed a self-review of my own code
[x] I have commented my code, particularly in hard-to-understand areas
[x] I have added unit tests for the code
[x] I have made corresponding changes to the documentation

Conclusion

All the modules and tests are running as expected. Also, the kotlin sample application is built like normal.

rudderlabs / rudder-sdk-android