Wrap Aws::ECS::Client into a result monad

[jollopre]

Deploy gem uses monads as an alternative to control flow of the program. Right now, if an exception occurs while executing methods from Aws::ECS::Client, we don't wrap it up with a result monad. This means, the program execution halts if any exception is raised.

We would like to control any exception raised within the client, an result result monad instead.