Signify private feeds

### What problem does this address?

Let's signify private feeds, for easier scanning and identification, as these might take priority for users.

### What is your proposed solution?

I've put together some quick specs on how these could look in the different type of listings we have:

[Figma link](https://www.figma.com/file/G60UqxPhTynbalo0Vfr1NC/Home-Concepts?type=design&node-id=434-4282&mode=design)

### Did you search for existing feature suggestions?

- [X] I have searched for existing feature suggestions.

Start with the attached image and the linked Figma file to understand the proposed private-feed treatment across the different listing types. Then locate the Android screens that render those listings; done means private feeds are visibly identifiable and consistently presented in each specified listing.

Written by the indexing model from the issue text.