Allow overriding connection while executing the sql magic.

[nkitsaini]

Describe your changes

Allow overriding connection while executing the sql magic. This is used in singlestore-labs/singlestoredb-python#47.

Issue number

Checklist before requesting a review

• Performed a self-review of my code
• Formatted my code with pkgmt format
• Added tests (when necessary).
• Added docstring documentation and update the changelog (when needed)

[kesmit13]

I'm not clear how this will have any effect in our notebook container since we are installing the official Jupysql package there.

[nkitsaini]

@kesmit13 We will update the notebook image to install this fork instead of installing from pypi. We have done the same for modifications to dash library: Dockerfile changes