Add framing serializer for other language(s)

[ERnsTL]

• As reference for implementers of libflowd in other languages.
• Upload existing libflowd-rs in Rust language
• Maybe in Java? Should be no more than two static methods.

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Case study Java:

• Write a wrapper component
• Calling Java objects from C/C++ using JNA
• Input: named pipes, forward into Java VM object by function call or something like a Go channel
• Output: receive from Java VM object, forward to named pipes
• Requires the Java component to conform to a (Java) interface, i.e. support a set of methods
• Not sure how useful this path is - takes away the generality of flowd which uses named pipes. OTOH, can quickly re-use Java libraries.
• Nothing is gained though because the component has to be specially-written anyway - whether to use named pipes or to conform to a component interface in order to be wrapped.
• Result: Implement framing format serialization for flowd components written in Java to use - just like for all other programming languages.