Migrate to androidx-media3 video player (#3857)

Behaviour is consistent with previous player except that:

- Swapping apps while a video is playing, and then returning to Tusky,
will keep the seek position in the video instead of returning to the
start
- The controls/media description can be shown by tapping anywhere, not
just on the video itself
- The media description is on-screen for the same duration as the player
controls (5 seconds here, 3 seconds in the previous code)
- The user has options to control the playback speed
- Rotating the device does not squash/stretch the video
- Show the media preview when playing audio-only files

Fixes https://github.com/tuskyapp/Tusky/issues/3329,
https://github.com/tuskyapp/Tusky/issues/3141,
https://github.com/tuskyapp/Tusky/issues/3126,
https://github.com/tuskyapp/Tusky/issues/2753,
https://github.com/tuskyapp/Tusky/issues/3508,
https://github.com/tuskyapp/Tusky/issues/3291

---------

Co-authored-by: mcc <andi.m.mcclure@gmail.com>

app/src/main/java/com/keylesspalace/tusky/view/ExposedPlayPauseVideoView.kt

@@ -1,41 +0,0 @@
-package com.keylesspalace.tusky.view
-
-import android.content.Context
-import android.util.AttributeSet
-import android.widget.VideoView
-
-class ExposedPlayPauseVideoView @JvmOverloads constructor(
-    context: Context,
-    attrs: AttributeSet? = null,
-    defStyleAttr: Int = 0
-) :
-    VideoView(context, attrs, defStyleAttr) {
-
-    private var listener: PlayPauseListener? = null
-    private var playing = false
-
-    fun setPlayPauseListener(listener: PlayPauseListener) {
-        this.listener = listener
-    }
-
-    override fun start() {
-        super.start()
-        if (!playing) {
-            playing = true
-            listener?.onPlay()
-        }
-    }
-
-    override fun pause() {
-        super.pause()
-        if (playing) {
-            playing = false
-            listener?.onPause()
-        }
-    }
-
-    interface PlayPauseListener {
-        fun onPlay()
-        fun onPause()
-    }
-}