Add the ability to block a contact

[Philippe-Choquette]

Checklist

• [X] I made sure that there are no existing issues - open or closed - to which I could contribute my information.
• [X] I made sure that there are no existing discussions - open or closed - to which I could contribute my information.
• [X] I have read the FAQs inside the app (Menu -> About -> FAQs) and my problem isn't listed.
• [X] I have taken the time to fill in all the required details. I understand that the bug report will be dismissed otherwise.
• [X] This issue contains only one feature request.
• [X] I have read and understood the contribution guidelines.
• [X] I optionally donated to support the Fossify mission.

Feature description

Add an option to block a contact, and indicate whether a contact is blocked

Why do you want this feature?

I believe it's a feature included in Fossify's Phone app, but for those who don't have that app (i.e., I'm currently satisfied with the Phone app by Google), it would make sense to have the feature in here too. The Google Contacts app does have the feature.

Additional information

No response