Communication: Moving cursor between concatened emojis not possible

[SimonKaran13]

Describe the bug

When you have a chain of emojis, e.g. 👍😄🇩‍🇪 you can't put the cursor between the emojis, only before the first emoji or after the last emoji.

To Reproduce

1. Go to course
2. Go to the communication tab
3. Go to a channel
4. Type a chain of emojis such as 👍😄🇩‍🇪👍😄🇩‍🇪👍😄🇩‍🇪👍😄🇩‍🇪
5. Try placing the cursor between the emojis (with mouse or with arrow keys)

Expected behavior

You should be able to move the cursor between the emojis to delete an emoji in the middle of the chain.

Screenshots

No response

Which version of Artemis are you seeing the problem on?

7.9.0

What browsers are you seeing the problem on?

Chrome

Additional context

Noticed this while reviewing #10242

Relevant log output