Add a simple audio / video trimmer.

[SuhasDissa]

Hey! I was looking through the issue history of the app and saw that you closed issue #54 saying that it's not supported by Android system APIs. But I found a system API that does support simple video trimming, and the AOSP gallery app uses it without any third-party libraries.

I added that feature to the app, and it seems to work fine. There are a few minor front-end UI/UX issues that I'll fix soon. But in the meantime, I'd love for you to take a look and let me know what you think.

Thanks!

[Bnyro]

This looks great at first view!
I haven't yet tested this, but such a functionality by using system APIs only is really awesome!

[Bnyro]

I think we should place the play button below the seekbar, between start: ... and stop: ... to make it look less squashed. (Though it's fine if we do that somewhen later)

I also noticed the recordings tab doesn't get updated when the trimming is done (since we run it on Dispatchers.IO now), but that can be changed in a different PR.

So it's good to be merged by you from my side :)
Works great, thank you for working on that!

[SuhasDissa]

TrimmerModel has some problem. It doesn't reset the timestamps when opening a new file

[SuhasDissa]

This is the only solution I could come up with

[Bnyro]

This is the only solution I could come up with

That should be fine in my opinion.
That way there's no edge case where startTimeStamp and endTimeStamp are not being resetted, so it's the probably the most safe option :)

[SuhasDissa]

@Bnyro What do you prefer? Merge or Squash and Merge

[Bnyro]

I combined the latest three commits since to clean up the commit history, now you can Merge the PR if you want :)