[Enhancement] Advanced response frequency config

[devgioele]

Allow users to specify separate response frequencies for specific phone numbers. For instance:

For 333 290 0000: 1 / message
For +44 222 0000: 1 / 1 hour
For +22 333 0000: 0 / message
For group "Group X": 1 / 2 hour
For everyone else: 1 / day

This would enable a personalized user experience. Some contacts might be confused by the message and so you might want to disable the message for them. Other contacts might tend to ignore the message and so one could consider increasing the response frequency just for those.