Merge String and DataStream to make Datastream usage implicit

Story

• We have a string type and a DataStream type and Steps to convert back and forth.
• Let's use the same type for both and do the conversions automatically.
• Simplifies sequences preventing the need to convert between strings and streams

Before:

Print (FromStream (ReadFile "C:/temp.txt"))

After:

Print (ReadFile "C:/temp.txt")