Put account / space / room headers next to each other

### Your use case

Element Web [has recently been redesigned](https://github.com/vector-im/element-web/issues/19526) in order to create a clearer hierarchy of global, per space, and per room actions. As a result, the spaces and rooms list now look like this:


It's a huge improvement over the old UI, but I think that the hierarchy can still be made clearer if the search bar is moved to the bottom and the account / space / room headers are put next to each other, like this:


See how similar elements would be distributed that way:


Versus how they are distributed with the current layout:


### Have you considered any alternatives?

_No response_

### Additional context

_No response_