Support "Low Priority" Rooms

### Your use case

#### What would you like to do?

I would like Low Priority rooms to be removed from the main app list (possibly configurable).

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

I would like the avoid having low priority rooms and conversations down out my more important conversations in the main conversation list. For example I am in many "community" rooms for general topics that I occasionally read, ask questions or respond to mentions. However these rooms tend to be much more active than my more involved conversations with many less people.

#### How would you like to achieve it?

Respect the `m.lowpriority` room setting and hide away these rooms from the default/main view.

### Have you considered any alternatives?

1. Continue using Element non-X. This is my current "solution".
2. Favorite my more important rooms. This solves some of the issues but has a very different UX, for example the default is not favourite so it is easy to lose new rooms or one-off messages from others.

### Additional context

Element X iOS issue: https://github.com/element-hq/element-x-ios/issues/2478

### Are you willing to provide a PR?

No