[Bug] Attempting to insert unicode characters breaks input and starts deleting characters

### Bug Description

While editing something, eg. a document, attempting to insert a Unicode character using `Ctrl+Shift+U` - the default keyboard shortcut on the majority of Linux systems - the insertion caret moves to the beginning of the current line and, if there's already text on said line, starts deleting characters as you type the value of the unicode character you want.

Furthermore, once the unicode character is inserted, the Unicode value, eg. `u30ad` is still there in the document, in addition to the unicode character.

Lastly, if you press `Enter` to insert instead of `Space`, that line sometimes becomes undeletable.

### How to Reproduce

On Linux:
- Create a new Document in AppFlowy
- Write a short string, eg. `test123`
- Press `Ctrl+Shift+U` followed by any Unicode code, eg. `30AD`, then press `Space` (if you press `Enter` instead of `Space` it tends to make it impossible to delete that line.

### Expected Behavior

I'd expect the insertion caret to stay, and a temporary indicator to show up like with most other applications on Linux - Firefox, for instance, shows an underlined `u` as a prefix, as well as underlining the Unicode code as you're typing, eg. u30ad.

### Operating System

Arch Linux

### AppFlowy Version(s)

v0.1.5

### Screenshots

_No response_

### Additional Context

_No response_