[Story] Public Room search NSFW filtering

[Velin92]

Description

• As a user I want the possibility of turning on and off such a filter (will be on by default, and this might be a stretch goal)
• As a user I want the results of the public room search to not contain any NSFW content if the filter is on
• As a user I also want the search to not get started if the search term contain any blocked/filtered term considered NSFW

Acceptance criteria

• TBD

Size estimate

S

Dependencies

• None

Out of scope

• Turning OFF the filter.

Open questions

### Questions
- [ ] What keywords should we filter?
- [ ] Should the keywords belong to different languages too? Should these other languages keywords only be used on specific locales or on all of them?
- [ ] Maybe the community could manage the keywords, and add them
- [ ] Do we also want to PREVENT completely the search if one of these keywords is search? or just filter out the rooms that contain any of these?
- [ ] Should we filter rooms based on name, topic or both?
- [ ] Could we use parental controls API to check if the filter can toggled? (Maybe we won't have it toggleable for the first iteration)
- [ ] Is this all really worth it? Public room search could be an internal feature only not available publicly

Subtasks

### Android

### iOS

### Rust
- [ ] https://github.com/matrix-org/matrix-rust-sdk/issues/3214

### Other

[Velin92]

We are also exploring the possibility of having the room search being not a public feature, but an internal feature only.

[Velin92]

We don't do any filtering since the public search will not be available publicly