Filter / Hide exchanges if account isn't linked

It would be useful to have the option to filter out exchanges (and thus their associated markets) that we are not actively trading on and/or haven't linked with Altrady. This could help optimize performance for users, as in theory there would be less market data and CBS signals needed to be fetched by a single user, as only the data from exchanges not filtered out by the user would be fetched and displayed in the app. Users shouldn't necessarily be fetching all market data from all exchanges, all the time. They should have an option to select the exchanges they actually care about.