* Re-organize files. Create MLIR backend classes

* WIP

* Refactored. Code compiles

* Moved context to Runtime class to outlive compilation and execution

* style-apply

* Base Runtime class. Few other modifications

* Minor fixes

* Fixed Runtime::run() to take type-erased pointer

* renamed core compiler

* rename backend compiler

* rename runtime compiler

* PR feedback

* Fix build fails

* - refactor LowerNGDialect
- addgraph pass to lower standardDialect to llvm module

* Addressed PR Comments

* i) Style fix ii) restore deleted file