Top level expression IR generation

include/dusk/IRGen/CMakeLists.txt

include/dusk/IRGen/IRGenerator.h

include/dusk/IRGen/Scope.h

lib/Frontend/Compiler.cpp

lib/IRGen/CMakeLists.txt

lib/IRGen/IRGenerator.cpp

lib/IRGen/Scope.cpp

lib/IRGen/TopLevelExpr.cpp

lib/IRGen/TopLevelExpr.h

lib/Parser/Parser.cpp