[fix]: minor storage lifetime optimization

[jamieQ]

Issue

• to support the mapRendering & mapOutput API, AnyWorkflow internally stores these transformations in a storage type
• the existing method implementations would retain the existing storage object unnecessarily, when only the existing transform need be retained

Description

• removed the unnecessary captures of the full internal storage object when mapping outputs/renderings

Checklist

• Unit Tests (existing tests suffice)
• UI Tests n/a
• Snapshot Tests (iOS only) n/a
• I have made corresponding changes to the documentation n/a

[jamieQ]

in the common use case, you have things like:

MyWorkflow()
  .asAnyWorkflow()  // creates internal storage
  .mapOutput { ... }  // creates new internal storage & would previously hold a reference to old storage
  .rendered(...)

now we won't keep the storage instances around longer than necessary.

[square-tomb]

Great catch!