Added remaining Monochrome / Ozone icons

[Jaffacakelover]

Lots of new Monochrome / Ozone icons, in SVG and PNG (compressed using Pinga).
Combined with #432, this should complete the to-do list in #433.

Thumbnail of all icons (click for full size):

Below are the icons that use logos (a concern raised in #432): A decision needs to be made if these need to be changed.

A few of the '-content' icons might be a bit small and need tweaking (such as 'Mobile-PalmOS-content').

[LibretroAdmin]

For now those look fine.

One small concern - all these files that are added with this PR, how many MBs does that add up to? At some point I guess we will have to research solutions on how we can combine some of these assets into one larger 'atlas' so we can reduce the amount of files (since loading lots of small files sequentially usually leads to slow disk I/O). Nevertheless, this is not a concern for your PR and it likely won't hold this back. I'd still like to know how many MBs in total all these added files are though.

[Jaffacakelover]

• #435 (this commit) = 2.15 MB (2,259,328 bytes)
• #432 = 0.5 MB (517,388 bytes)
• retroarch-assets (2022-07-24, ozone & monochrome, png & src (not inc. ttf)) = 3.84 MB (3,842,521 bytes)
• Above 3 combined = 6.62 MB (6,619,237 bytes)
  ...
• retroarch-assets (complete repo 2022-07-24) = 613 MB (643,236,521 bytes)

[baxysquare]

@LibretroAdmin We'd like to tackle the MB bloat issue caused by retroarch-assets through moving to a Unified Theme format that will benefit all the UXs. Part of that proposal is that SVG sources be required, and the PNG files in any needed size would be created by batch script. The project is on the to-do list for @jdgleaver.

[hizzlekizzle]

jdgleaver is on indefinite hiatus / retired, so we probably shouldn't wait on him :P

[baxysquare]

@hizzlekizzle That's good to know. That means we'll need some help getting it implemented as outlined in #345. It's a worthy cause that would greatly benefit the main project.