Add access token as a param in cdn link and minor improvements

Summary:
This fixes two issues. One issue where the recent change of cdn to lookaside hostname broke our build download process. More about this can be found [here](https://fb.workplace.com/groups/flipperfyi/permalink/772986153467682/).
It also fixes a bug which occurred on a retry when an error happened. Recently I made changes where, if the build is downloaded then retrying shouldn't redownload it. But we used to remove the downloaded builds after install phase, so this diff just removes the build when the download is successfull.

Reviewed By: nikoant

Differential Revision: D23372251

fbshipit-source-id: b57e69f65a20fc123191962d60165a62859d4ef7

desktop/app/src/fb-stubs/user.tsx

@@ -83,3 +83,9 @@ export async function getFlipperMediaCDN(
 export async function getPreferredEditorUriScheme(): Promise<string> {
   return 'vscode';
 }
+
+export const appendAccessTokenToUrl: (
+  url: URL,
+) => Promise<string> = async () => {
+  return Promise.reject(new Error('Implement appendAccessTokenToUrl'));
+};

desktop/app/src/index.tsx

@@ -188,7 +188,7 @@ export {Console} from './ui/components/console';
 export {default as Sheet} from './ui/components/Sheet';
 export {default as FileSelector} from './ui/components/FileSelector';
 export {KeyboardActions} from './MenuBar';
-export {getFlipperMediaCDN} from './fb-stubs/user';
+export {getFlipperMediaCDN, appendAccessTokenToUrl} from './fb-stubs/user';
 export {Rect} from './utils/geometry';
 export {Logger} from './fb-interfaces/Logger';
 export {getInstance as getLogger} from './fb-stubs/Logger';