C: Prospective Ideas #1575

The C backend currently supports almost all the integration tests and I think it's time to introduce some additional features toC. Some of the possible extensions and improvements to this backend can be:

• Support ASR optimization passes. I'd wait until we finish ASR Passes refactoring.(C: Support passes #1636)
• Using the --fast flag to optimize the code by let's say using the x.m_value wherever possible and any other optimizations wherever possible. (Support fast option in C #1580 )
• Directly compile using --backend=c #1601
• Import from C Header File #541
• Semantics of p_c_pointer and PointerToCPtr #592
• pointer(x) doesn't update x in CPython #670

Please free to edit/suggest any other ideas that you would like to have @certik @czgdp1807 @rebcabin.