fix(spotify-web): various unthemed elements

[Papweer]

🔧 What does this fix? 🔧

Themes the previously unthemed Accept Cookies banner, vendors info popup and the signup banner. Also fixes the left sidebar background on the main page being unthemed.
fixes #834 and also fixes #826

🗒 Checklist 🗒

• I have read and followed Catppuccin's contributing guidelines.
• I have updated the version appropriately in the ==UserStyle== header of the catppuccin.user.css file.

[uncenter]

Please follow the https://www.conventionalcommits.org/en/v1.0.0/ format for titling your pull request. In this case, the type of change is a fix, the scope should be spotify-web, and the body should be a very succinct summary of your changes.

[Tnixc]

We still have some unthemed elements, we might want to theme those as well before we merge

[Papweer]

I themed the unthemed elements mentioned above and a few more. Not sure what to do with the cookie banner theming but for now I just left it in.

[Tnixc]

Glad you fixed the elements above. There's still some minor things to fix here. Make sure you update the version from 0.0.1 to 0.0.2, It seems like its gone back to 0.01 in your latest commit.

[uncenter]

I themed the unthemed elements mentioned above and a few more. Not sure what to do with the cookie banner theming but for now I just left it in.

Yeah sorry about that random discussion. Leave it in for now, I'll make a PR changing it if we decide on something :)

[Papweer]

I themed the remaining elements. I couldn't find any other unthemed elements but I might have missed some.

[Papweer]

I fixed the linting errors. I think it's ready to merge.