Adds a notifyAvailableUpdate flag to config.json to disable update (#3992)

Summary:
We would like to version control Flipper and some of our custom plugins that are installed on developers' systems.
Flipper by default prompts users to upgrade so they sometimes do the update and then all our custom plugins break because they were compiled for an older version.
See https://github.com/facebook/flipper/issues/3947 for feature request info.

## Changelog

Adds notifyAvailable flag to config.json to disable prompting for users that "an update is available"

Pull Request resolved: https://github.com/facebook/flipper/pull/3992

Test Plan:
Tested by running locally.
Had to comment out the isProduction() check to confirm this it worked properly because this flag is false on dev versions.
Couldn't figure out how to manually test the handleOpenPluginDeeplink.tsx change but made a similar change there; happy to test that if you can tell me how to exercise that path.

Reviewed By: antonk52

Differential Revision: D39654481

Pulled By: antonk52

fbshipit-source-id: cef6b48d870915c48f620269c42d24b8ef1f4c29

desktop/flipper-common/src/settings.tsx

@@ -76,7 +76,7 @@ export type LauncherSettings = {
   ignoreLocalPin: boolean;
 };
 
-// Settings that primarily only apply to Eelectron atm
+// Settings that primarily only apply to Electron atm
 // TODO: further separte between flipper-ui config and Electron config
 export type ProcessConfig = {
   disabledPlugins: string[];
@@ -90,6 +90,8 @@ export type ProcessConfig = {
   launcherMsg: string | null;
   // Controls whether to delegate to the launcher if present.
   launcherEnabled: boolean;
+  // Control whether to suppress "update available" notifications
+  suppressPluginUpdateNotifications?: boolean;
 };
 
 export type Platform =