[MM-59543] Disallow use of file: protocol in the app, remove all references to it, add mattermost-desktop: protocol to read local files (#3095)

src/main/preload/internalAPI.js

@@ -72,7 +72,6 @@ import {
     START_UPDATE_DOWNLOAD,
     START_UPGRADE,
     TOGGLE_DOWNLOADS_DROPDOWN_MENU,
-    GET_DOWNLOADED_IMAGE_THUMBNAIL_LOCATION,
     DOWNLOADS_DROPDOWN_OPEN_FILE,
     MODAL_CANCEL,
     MODAL_RESULT,
@@ -110,10 +109,6 @@ contextBridge.exposeInMainWorld('timers', {
     setImmediate,
 });
 
-contextBridge.exposeInMainWorld('mas', {
-    getThumbnailLocation: (location) => ipcRenderer.invoke(GET_DOWNLOADED_IMAGE_THUMBNAIL_LOCATION, location),
-});
-
 contextBridge.exposeInMainWorld('desktop', {
     quit: (reason, stack) => ipcRenderer.send(QUIT, reason, stack),
     openAppMenu: () => ipcRenderer.send(OPEN_APP_MENU),