Request to improve the accessibility of Elemend-desktop for Linux

### Steps to reproduce

1. Where are you starting? What can you see?

Linux distribution Solus, with the latest updates. Screen reader Orca (latest and Master). MATE Desktop (1.26).
I also add in ~/.profile:

export ACCESSIBILITY_ENABLED=1

This is important because in my case Element-desktop is not accessible without this variable.

2. What do you click?

Using either the program launch dialog (ALT+f2), or the Risk Menu (super key), or the MATE main menu (ALT+F1), I launch Element.

3. More steps…

3.1. I try to select any text using Shift and right arrow, and CTRL+Shift+right arrow.
3.2. In the room tree, I switch to focus mode (this is a function of the Orca screen reader), and try to use the up and down arrows to select a room. I also press the arrows to the right and left.

### Outcome

#### What did you expect?

3.1. The text is selected, and Orca informs about the selected text.
3.2. In the tree rooms when you press the cursor up and down, Orca reports the item on which the focus is. Orca also reports the status of the branch (collapsed or expanded).

#### What happened instead?

3.1. Text is not selected, Orca does not report anything.
3.2. Orca reports nothing.

All of the above works great in the web version.

### Operating system

Solus

### Application version

1.9.4

### How did you install the app?

sudo eopkg install element

### Homeserver

matrix.org

### Will you send logs?

No