Refine top right icons in header menu

[niquewoodhouse]

Problem

As discovered in #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