Extension executable
Extension manifest files define the executable file spawned by Amazon DCV. Amazon DCV will exchange messages with the extension using 
				the stdin and stdout of the extension process.
- The Amazon DCV client starts the extension once a Amazon DCV connection is established. The executable runs in the context of the user who launched the client. 
- The Amazon DCV server starts the extension when a user logs in. The executable runs in the context of the logged-in user.