Enhancing MLIR Backend for LFortran

LFortran's MLIR(Multi-Level Intermediate Representation) backend executes fortran code via LLVM dialect of MLIR, but requires major refactoring with every new MLIR version. This is because it calls unstable MLIR C++ APIs directly, which gets changed with MLIR version changes. This project focuses on finding the right design to solve this problem. Multiple approaches will be studied and compared including studying projects which support MLIR to identify the most stable and maintainable architecture. The best design will then be implemented and validated. The deliverable is a redesigned MLIR backend that is stable across MLIR versions, requiring minimal refactoring for adding support for newer versions in future.