[Feature Request]: Inline user playlists in sidebar on desktop view

### Guidelines

- [X] I have searched the issue tracker for [open](https://github.com/FreeTubeApp/FreeTube/issues?q=is%3Aopen+is%3Aissue) and [closed](https://github.com/FreeTubeApp/FreeTube/issues?q=is%3Aissue+is%3Aclosed) issues that are similar to the feature request I want to file, without success.
- [X] I have searched the [documentation](https://docs.freetubeapp.io/) for information that matches the description of the feature request I want to file, without success.
- [X] This issue contains only one feature request.

### Problem Description

The flow of accessing favorites is more jarring for desktop view with the inclusion of user playlists, now having to click the Playlist tab, wait for the `/userPlaylists` route to load, then click my desired playlist to get where I want to be. It would be desirable if I didn't have to do two actions to access my playlist of choice (as was the case before).

### Proposed Solution

Inline the user playlists in the side nav for the desktop view, much like the YT implementation. This makes this for a more streamlined UX flow that matches how I used it before.

One major question is what we do with the Playlists tab on the desktop view. I say hide it because it then no longer serves a real purpose other than easy access to the "Create New Playlist" button. We can probably add an "Add New Playlist" button as a sidenav option to compensate.

Another major question is if we add a "Show more" / "Show less" button like YT. I say yes to this as well, because users might have a significant number of playlists.

A third major question is if we show a playlist that exists outside of the "Show more". Yes: the quick bookmark target.

Nothing should be changed at all on the mobile view.

### Alternatives Considered

- Keep Playlists tab on desktop view below all playlists in lieu of an inline "Create new playlist" button.
- Place items in top nav instead of side nav (bad idea - too short/valuable of real estate, and isn't where users recognize it to be).
- No "Show more" / "Show less" button in MVP (it's not going to be the worst thing ever, but some users will be pretty severely impacted. I see no reason to rush this out the gate).

### Issue Labels

ease of use improvement, improvement to existing feature

### Additional Information

_No response_