Composer focus lost when applying mark-up to full line in multi-line text

### Steps to reproduce

1. Focus the message composer / text input
2. Enter "foo"
3. Hit SHIFT + Enter to start a new line
4. Use the keyboard to navigate back to the first line ("foo")
5. Use the keyboard to select the entire first line
6. Hit CMD + B to bold the selected text
7. Notice that the line is wrapped in `**` but the composer loses focus. To continue typing, you have to refocus it, e.g. by clicking into it.

### Outcome

#### What did you expect?

The editor to keep focus with the cursor being placed either at the beginning or the end of the line.

#### What happened instead?

The editor lost focus.

### Operating system

macOS

### Application version

Element version: 1.12.12 Crypto version: Rust SDK 0.16.0 (82e97d4), Vodozemac 0.9.0

### How did you install the app?

Element website

### Homeserver

matrix.org

### Will you send logs?

No