Allows to trim videos on Android, including UI.

• Code based on "k4l-video-trimmer" library, to handle various issues on it, that I've asked about here and [here] .
• Trimming is done by using "mp4parser" library (that was used on the original library) and on this answer, which is based on the Gallery app of Android.
• This library handled various issues that the original had, while also having 100% code in Kotlin.
• At first it was a fork, but as it became completely different in code, and because the original one isn't maintained anymore, I decided to create this one as a new repository.