[Approved] Plasma 6 Proposal: Add new Blue Ocean sound theme to Plasma

The new Blue Ocean sound theme is finally here. It is meant to replace Oxygen sounds and add new sounds that improve usability, like those for un/plugged devices. Oxygen still offers some sounds that this theme does not replace, mainly sounds for instant messaging apps and window actions like minimizing or maximizing.

The files for the Blue Ocean sound theme can be found in this repository: https://invent.kde.org/plasma/ocean-sound-theme

There is also another theme called Harmony made by Gianmarco which can be found here: https://dl.gianmarco.ga/Dream%20Sounds/Harmony/%21Download%20all%20v1.3.zip

Here are other technical changes that are needed to make this a reality:

Blocker bugs:

• The Start-up sound is not played: https://bugs.kde.org/show_bug.cgi?id=422948 (fixed by: !2313 (merged))

Changes needed:

• Un/plugging USB device should produce sound (!2106 (merged))
• Sounds could follow XDG spec: #47 http://0pointer.de/public/sound-theme-spec.html and http://0pointer.de/public/sound-naming-spec.html
• Use custom sound for changing the volume: plasma-pa!202 (merged)

All sounds in the Blue Ocean sound theme are in 16-bit, 48000hz .oga targeting 320Kbps VBR, normalized using the ReplayGain plugin in Audacity. The XDG spec does not specify a specific normalization level, only that "The sound samples must be normalized with a suitable average replay level, in order to be properly mixed down.". I used Windows sounds as a reference and noticed their volume is unchanged when using ReplayGain with a -3dB gain, so that's the value I'm using.