Initial implementation of SSA Transform

[dibyendumajumdar]

The implementation is based on description in 'Engineering a Compiler' and the paper 'Practical Improvements to the Construction and Destruction of Single Static Assignment Form' by Preston Briggs.

Implementation is here: https://github.com/CompilerProgramming/ez-lang/blob/main/optvm/src/main/java/com/compilerprogramming/ezlang/compiler/SSATransform.java