Make Gravatar configurable from dashboard (enable/disable)

Posting from GH:

Gravatar is great. But sometime we want to disable.

I have a client who’s serving only the market in Japan.
In order to reduce the number of the spam, they block in-and-out access from overseas by IP address.

This led to the consequence that their Mautic is unable to access Gravatar.

My current solution is to override the code like the following

I thought that it would be easy if we can add configurable setting in dashboard.

For example… just simple checkbox…

[Check] Use Gravatar?