Can we add dropshadow on Tooltips?

Hi! It is me again. It would be great if we can also add dropshadow option on the tooltips.

Thank you very much!! You are awesome!!

The issue names no files, tests, or entry points; start by locating the tooltip implementation in the Flutter chart widgets and checking how existing tooltip options are configured. Done means tooltips expose a dropshadow option and the behavior is covered by the relevant tooltip tests, if present.

Written by the indexing model from the issue text.