Allow user to view and revoke token allowances

Given I have granted a token allowance, then I want to be able to be able to:

* View a list of all dapp token allowances
(Accessible from connected dapp details & settings?)

* See details of each allowance and have the ability to revoke allowance

The issue names no files, tests, or entry points, so begin by mapping the connected dapp details and settings flows in the TypeScript extension. Define the scope for listing dapp token allowances, displaying allowance details, and revoking them, then identify tests covering those flows before implementation.

Written by the indexing model from the issue text.