[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/types/downloads.ts

@@ -18,6 +18,7 @@ export type DownloadedItem = {
     receivedBytes: number;
     totalBytes: number;
     bookmark?: string;
+    thumbnailData?: string;
 }
 
 export type DownloadedItems = Record<string, DownloadedItem>;

src/types/external/file-types.d.ts

@@ -4,3 +4,4 @@
 declare module '*.mp3';
 declare module '*.svg';
 declare module '*.lazy.css';
+declare module '*.jpg';

src/types/window.ts

@@ -27,9 +27,6 @@ declare global {
         timers: {
             setImmediate: typeof setImmediate;
         };
-        mas: {
-            getThumbnailLocation: (location: string) => Promise<string>;
-        };
         desktop: {
             quit: (reason: string, stack: string) => void;
             openAppMenu: () => void;