fix: allow copying from editable void input

[alex-vladut]

Description
Copying from an editable void ends up with the whole void element being copied instead of the selected text only. I added a fix so that, when the target of the event is an input field it won't apply the regular Slate logic for copying and instead will just rely on the default browser's functionality.

You'll notice in the video that there is still a not-ideal use case where, if a section of text is selected from an editable void it still ends up copying the whole element, not just the text. This kind of approach is useful to enable, for example, copying a non-editable void element such as a mention. Let me know please if someone has a better idea of how to better handle it.

Issue
Fixes: #5366

Example

copy-from-editable-void.mov

Context

Checks

• The new code matches the existing patterns and styles.
• The tests pass with yarn test.
• The linter passes with yarn lint. (Fix errors with yarn fix.)
• The relevant examples still work. (Run examples with yarn start.)
• You've added a changeset if changing functionality. (Add one with yarn changeset add.)

[changeset-bot]

🦋 Changeset detected

Latest commit: 9cfe24f

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
slate-react	Patch

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