Offer three preset “ping” sounds

### Your use case

#### What would you like to do?

Offer three different kinds of notification sounds;
- Unintrusive
- Normal
- High prioritity

These differ in sound profiles, while Unintrusive could easily blend in with background sounds, High Priority would absolutely not, and Normal sits somewhere between the two.

#### Why would you like to do it?

These sounds, and the ability to set these to different rooms/events/times, would help someone effectively navigate or be alerted to different priorities.

This issue is related (but distinctively different to) setting custom sounds, as this one makes it possible to, with minimal effort, to have a variety of noises to pick from. The reason why this would be better over someone picking their own noise, is that Designers have much more experience as to what could work for the human ear, and what not. This does not exclude custom sounds, and someone having one, but it would make for “pleasant presets”, that just instantly \*snap* works for them.

This issue also aims to inform and expand upon https://github.com/vector-im/element-web/issues/5891, to possibly take this feature request into wider context when solving that issue.

(The feature to set these sounds to different situations is for another issue to request, this issue exists to inspire Design to make those sounds)

### Have you considered any alternatives?

_No response_

### Additional context

_No response_

No files, tests, or entry points are identified in the issue. Start by reviewing the related notification-sound issue and the existing notification audio design, then define three distinct preset sound profiles and document what design approval and playback behavior would constitute completion.

Written by the indexing model from the issue text.