Rename `BnXXX` to `BNXXX`

[chokobole]

Issue type

Feature Request

Current behavior?

We mixed using BNXXX or BnXXX.

BNCurve and BN254Config are the case starting with BN
Bn254SHPlonkProverXXX, Bn254ProvingKeyXXX and kIsBn254XX are the cast starting with Bn.

Expected Behavior?

Choose one of the styles and apply the style to every case.