Regenerate some drawables to their latest design

[TacoTheDank]

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

• Deleted unused drawables
• Regenerated some drawables to their latest design

Icons with visible differences:

• ic_next
• ic_palette
• ic_playlist_add
• ic_playlist_add_check
• ic_playlist_play
• ic_previous
• ic_search_add

Most of these are barely visible changes, but they ARE there. Only one is definitely noticeable, though (ic_playlist_play).

Before	After

If you want, you can create two tabs with "https://yqnn.github.io/svg-path-editor/" and copy-paste the old and new pathData in each tab respectively. That'll help you understand the changes more. (For drawables with multiple paths, simply copy-paste the first pathData, add a space, and then copy-paste the second pathData, etc.)

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.

Due diligence

• I read the contribution guidelines.

[litetex]

LGTM

Tested the app "superficial" by checking the UI and didn't find any bigger problems