Restore cursor shape behaviour for Emacs mode

[pinn3]

Description

I have my cursor configured to be a block character in my terminal emulator because it's more visible to me

Checklist

• I've added this contribution to the changelog.rst.
• I've added my name to the AUTHORS file (or it's already there).

• I installed pre-commit hooks (pip install pre-commit && pre-commit install).
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• Please squash merge this pull request (uncheck if you'd like us to merge as multiple commits)

[dbaty]

I can confirm the fix:

before:

after:

I'll review that this week (I don't know this part of the code). Thanks for your contribution.

[j-bennet]

This looks good to me, according to the docs here, ModalCursorShapeConfig is meant for vi mode.

[j-bennet]

Thanks @pinn3 , merging.