Add support for setting the Response Meta.Ttl field

### What problem are you facing?
With the advent of Realtime Compositions there is no standard reconciliation interval and the composition function pipeline will only be executed when a change is detected in a watched resource or when the TTL for the pipeline expires.

Since there are no watches on EnvironmentConfigs or ExtraResources, changes to these resources _will not_ trigger a reconciliation, but will be detected when the current pipeline TTL expires. By default the TTL is 1 minute for all Go SDK-based functions. Users may want to be able to set the TTL of the pipeline to a higher or lower value to detect these changes as needed.

### How could this Function help solve your problem?

The function should support the ability to set the response Meta.Ttl field as specified either by the composition developer in a function input or programmatically at runtime based on a calculation, or both.