Read-only entity element can't be deleted by pressing backspace key when using Android IME

[Rain-Zheng]

Describe the bug
When using Android soft keyboard (Gboard), the read-only entity element can't be deleted by pressing backspace. Similar to some previous issues, the root cause is some Android IMEs don't support KeyboardEvent.key and this value will always be 229(Unidentified). To workaround the compatibility issue, we should use InputEvent instead.

We may need to handle InputEvent in at least 2 plugins:

• EditPlugin, it should dispatch the input event to entityFeatures. And the related features including RemoveEntityBetweenDelimitersFeature, DeleteBeforeEntityFeature, BackspaceAfterEntityFeature should also support input event.
• ContentModelEditPlugin and its related logic like keyboardDelete should support input event.

To Reproduce
Steps to reproduce the behavior:

1. Insert a read-only entity into the demo editor
2. Try to delete it using Android IME

Screenshots

Screen_Recording_20240109_184256_Chrome.mp4

Device Information

• OS: Android
• Browser Chrome
• Version 119

Additional context
Similar issues:
#513
#2061

[Rain-Zheng]

@JiuqingSong could you take a look at this issue?

[JiuqingSong]

Thanks for reporting. Would you like to contribute a fix?

Thanks.

[Rain-Zheng]

@JiuqingSong I created a PR: #2402, could you take a look when you have time? Thanks.