Remove broken "Consensus" tab from UI and related code (#434)

* Remove consensus-tab related stuff, and unused messages, from the telemetry backend

* also remove AfgAuthoritySet feed message, and handle same from node

* Blat everything consensus related that I can find in the UI

* cargo fmt

* README: had -> has

Co-authored-by: David <dvdplm@gmail.com>

Co-authored-by: David <dvdplm@gmail.com>

frontend/src/components/Chain/Header.tsx

@@ -90,14 +90,6 @@ export class Header extends React.Component<Header.Props, {}> {
             current={currentTab}
             setDisplay={setDisplay}
           />
-          <Tab
-            icon={consensusIcon}
-            label="Consensus"
-            display="consensus"
-            tab="consensus"
-            current={currentTab}
-            setDisplay={setDisplay}
-          />
           <Tab
             icon={settingsIcon}
             label="Settings"