Support .env vars in annotations

Per Whisk documentation (https://github.com/apache/openwhisk/blob/master/docs/annotations.md#annotations-specific-to-web-actions) and Adobe documentation (https://developer.adobe.com/runtime/docs/guides/using/securing_web_actions/) OpenWhisk has the ability to secure a web action behind a specified header value. When the header value is placed in the .env file the expectation is that the require-whisk-auth variable will be populated with the environment variable value however this is not happening

### Expected Behaviour
require-whisk-auth value is that of the specified .env variable

### Actual Behaviour
$auth_hash is not replaced with the actual value so the require-whisk-auth variable ends up having a value of '$auth_hash'

### Reproduce Scenario (including but not limited to)
Within a web action annotations add value
require-whisk-auth: $auth_hash

Within .env add auth_hash=my_value

#### Platform and Version
Latest