Adding Option to add Custom Shadow to Charts

this issue is siimilar to #1482 but it only implements shadow, I am trying to implement something which can even have glow instead of just shadow.

this is the design I am trying to implement.

Review related issue #1482 and the linked design image first. The request is to support custom chart shadows and glow effects rather than shadow alone, but it does not identify affected files, tests, or a completion criterion.

Written by the indexing model from the issue text.