Grey out watched videos

[yy-385]

What is it?

• Bugfix (user facing)
• Feature (user facing)
• Codebase improvement (dev facing)
• Meta improvement to the project (dev facing)

Description of the changes in your PR

• Updated the UI to include a toggle switch in the Audio/Video settings page, allowing users to control the grey-out feature for unwatched videos.
• Modified the updateFromItem method in the StreamInfoItemHolder class to apply the grey-out logic based on the toggle’s state (on/off).

Before/After Screenshots/Screen Record

• Before:

• After:

Fixes the following issue(s)

APK testing

The APK can be found by going to the "Checks" tab below the title. On the left pane, click on "CI", scroll down to "artifacts" and click "app" to download the zip file which contains the debug APK of this PR. You can find more info and a video demonstration on this wiki page.

I Tested the APK using the Android Studio Emulator with the following steps:

1. Installed the APK on the emulator running Android 13.
2. Verified the toggle in Audio/Video settings enables and disables the grey-out feature correctly.
3. Checked that the grey-out effect applies to watched videos when the toggle is on.
4. Ensured the toggle setting persists after restarting the app.
5. Confirmed no crashes or unexpected behavior during testing.

The feature works as expected in both light and dark modes.

Due diligence

• I read the contribution guidelines.

[opusforlife2]

@yy-385 ?