Manually connect my current account to the current site

As a dapp user, I'd like to connect my current account to the current site I'm viewing from within MetaMask, so that I will be able to use MetaMask with that site more easily.

**Description**

We should allow users to manually connect to a dapp/site they're currently browsing from within MetaMask. This is important because in many instances, users are forced to reload the page, or have trouble finding the connect button in the UI of the many different dapps. If we can give a reliable place to initiate a dapp connection, this is helps alleviate this problem.

Adding a site manually should take the user to the Connect Flow, currently represented in designs:

**Designs**
Link allowing users to manually connect to account: https://www.figma.com/file/CvD7nhQVeSEB1QuSy3XhtY/oCap-Login-Per-Site?node-id=955%3A353

**AC**

* Test coverage