Refine top right icons in header menu

### **Problem**

As discovered in https://github.com/vector-im/element-web/issues/19706 we believe the options on the right side of the room header might confuse users as:

- they expect the room header to be exclusively about the selected room
- the number of icons makes it harder to quickly scan and find what a user wants to find
- the icons themselves might not represent to users what they'll discover after clicking

### **Task**

- [ ] Create alternative header options aiming to give users more clarity on options, and still provide easy and expected access to notifications
- [ ] Set up user testing sessions to test if these work with cohorts of new users and experienced users