Multiple Helper app bundles required on macOS starting with M76 (3809 branch)

[Marshall Greenblatt]

CEF Helper app bundle requirements on macOS have changed starting with 3809 branch as described below. These changes are necessary to support the application of different entitlements for each Helper type with notarizing apps for macOS Catalina.

Your app must now contain 4 different Helper app bundles in the "<appname>.app/Contents/Frameworks" directory:

• <appname> Helper.app
• <appname> Helper (GPU).app
• <appname> Helper (Plugin).app
• <appname> Helper (Renderer).app

These app bundles may be identical except for the name and related Info.plist attributes. Chromium will internally search for and execute the associated Helper whenever a particular process type is required. See issue #2737 for additional details and example CMake configuration changes that can be used to generate these Helpers.