[Zellic] 1 missing input validation on user inputs

[manishbista28]

Fixes
#50

Includes

• field bound check
• on-curve check
• on-subgroup check

For

• groth16_verify
• groth16_verify_compressed

[manishbista28]

Commit Details:

3bb848b for subgroup check
9205ecf for field bounds check
d341c7c to 36f33d7 for on-curve check on compressed serialized input
6e4bb3c for on-curve check on uncompressed deserialized input
aae3e77 to merge all of these types of validation checks

[manishbista28]

The same changes have also been done through
PR #34 , #35 and #38
Will close them if it's easier to review directly through this PR. @AaronFeickert