Feature Request: "Focused" subset of Inbox

There is an excellent feature in the Outlook mail App for Android that gives 2 subsets of the Inbox. It essentially separates messages into those from friends and those from businesses: There is an option to click on a "Focused" button or an "Other" button.

Focused - shows all email from single sources (perhaps these are email addresses it finds in the Contacts)

Others - these are generally the email messages from subscriptions or businesses.

This is a really convenient feature that I would love to see included in K-9 mail!

Here is what it looks like in the Outlook App...

Expected behavior

When Inbox is open, you click on the word "Focused" and it shows only email received from individuals. When you click on the word "Other" it shows all other email.

Actual behavior

This is a feature request. It hasn't been implemented yet.

Steps to reproduce

Environment

K-9 Mail version:

Android version:

Account type (IMAP, POP3, WebDAV/Exchange): all

Start by reviewing the Inbox screen and the requested Focused and Other views, using the Outlook example and expected behavior as requirements. The issue does not name implementation files or tests, and the classification rules for individuals, contacts, subscriptions, and businesses need to be defined. Done means Inbox users can switch between both subsets and each shows the intended messages.