Redesign the player icons to eliminate sharp edges / be rounder

### Checklist

- [X] I have used the search function for [**OPEN**](https://github.com/AntennaPod/AntennaPod/issues) issues to see if someone else has already submitted the same feature request.
- [X] I have **also** used the search function for [**CLOSED**](https://github.com/AntennaPod/AntennaPod/issues?q=is%3Aissue+is%3Aclosed) issues to see if the feature was already implemented and is just waiting to be released, or if the feature was rejected.
- [X] I will describe the problem with as much detail as possible.
- [X] This request contains only one single feature, **not** a list of multiple (related) features.

### App version

3.3.2

### Where did you get the app from

Google Play

### Problem you may be having, or feature you want

To be perfectly honest, I have never been a fan of the way the player icons look. I think the sharp edges are ugly. I want to finally change that.

### Suggested solution

I have decided to replace them with rounder versions from https://fonts.google.com/icons?icon.set=Material+Icons. I also decided to use the [Google Material-designed speed icon](https://fonts.google.com/icons?selected=Material+Icons+Outlined:speed:&icon.query=speed&icon.set=Material+Icons&icon.style=Rounded) as well.

Two potential issues still exist:
- ~~A new animation will need to be created for the new playback speed icon. (Only if an animation is wanted, otherwise it can just be static.) Alternatively we can just use the original, even though I personally think the new one looks better and is more congruent with material design.~~ No more as of #7401.
- The new play/pause animation looks a little bit strange. I tried my best to make one using [vectalign](https://github.com/bonnyfone/vectalign). (I don't have experience creating vector animations, so hand-created is probably out of the question for me.)

Relevant branch: https://github.com/TacoTheDank/AntennaPod/tree/playerRoundedDesign

Test APK:
[app-play-debug playerRoundedDesign.zip](https://github.com/AntennaPod/AntennaPod/files/14881488/app-play-debug.playerRoundedDesign.zip)

### Screenshots / Drawings / Technical details

[playerRoundedDesign screenshots.zip](https://github.com/AntennaPod/AntennaPod/files/14881657/playerRoundedDesign.screenshots.zip)