Show connected sites and option to disconnect from them

**Describe the usability problem**
I couldn't find any settings option to see a list of connected sites to which my wallet is connected at the moment. This feature is available in the Chrome Extension and would love to have the same in MetaMask Mobile app.

**Screenshots**

**Expected behavior**
Show an option somewhere in the app to see a list of connected sites and an option/button to disconnect from those sites.

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**User impact | Usage frequency | Feasibility scores**
_How important is this to the user, what the user wants to accomplish | Daily, weekly, monthly | Small, medium, large_

No files or tests are named. Start by locating the MetaMask Mobile settings and existing dapp-connection flow, then compare the expected behavior with the Chrome Extension screenshots. Done means the app shows connected sites and provides a way to disconnect from them.

Written by the indexing model from the issue text.