[Refactor] Cleanup and refactor of the code for analysis of parallel loops and loop interchange

[jjfumero]

Description

Cleanup and refactor of the code for analysis of parallel loops and loop interchange. This PR also eliminates old code no longer needed. Loop reordering option renamed to loop.interchange. This option is enabled by default.

Problem description

n/ a.

Backend/s tested

Mark the backends affected by this PR.

• [X] OpenCL
• [X] PTX
• [X] SPIRV

OS tested

Mark the OS where this PR is tested.

• [X] Linux
• [x] OSx
• [ ] Windows

Did you check on FPGAs?

If it is applicable, check your changes on FPGAs.

• [ ] Yes
• [X] No

How to test the new patch?

make
make tests