Small UI fixes (#3966)

* Load dapp visibility from localStorage

* Align MethodDecoding address svg properly

* Consolidate svg & img classes overrides

* improve isNullAddress check

* readOnly for null display

* disabled || readOnly

js/src/views/Dapps/dappsStore.js

@@ -46,6 +46,7 @@ export default class DappsStore {
   constructor (api) {
     this._api = api;
 
+    this.readDisplayApps();
     this.loadExternalOverlay();
     this.loadApps();
     this.subscribeToChanges();