V3.2.0: many important improvements (#1321)

[gfursin]

I added many important features to CMX pending for a very long:

• added utils.test_input to test if input has keys and report them as error
  • added prefix_cmx key to cmr.yaml to customize cmx pull repo
• improved CMX logging (-log and -logfile): [CMX] add logging of main functions mlcommons/ck#1317
• print control flags in help (cmx -h | cmx -help): [CMX] print control flags in help mlcommons/ck#1318
• fail if control flag is not recognized: [CM/CMX] check control flags for CM/CMX access function and fail if flags/keys are not recognized mlcommons/ck#1315
• added -repro flag to record various info to cmx-repro directory: [CMX] add -repro flag to CMX core mlcommons/ck#1319
• print call stack when error > 32 to be able to trace error cause: [CMX] print call stack when error > 32 mlcommons/ck#1320
  can be combined with -log=debug and -logfile