Add a with-crypto cabal flag to build Plinth/Plutus scripts without system crypto C libraries

[zeme-wana]

Problem
Compiling a Plinth script transitively pulls cardano-crypto-class, which forces the system C libraries libsodium/libblst/libsecp256k1 at cabal-solve time (cabal#4087).
Script authors must install these even though compiling a script never runs any crypto.

Change
New with-crypto flag on plutus-core (default on, mirrored on plutus-metatheory).
The 6 PlutusCore.Crypto.* modules are now CPP-gated:

Tests
New crypto-hash-parity-test: 114 goldens (6 hashes × 19 inputs, incl. block/padding edge cases) generated by the +with-crypto build (cardano-crypto-class) and reproduced byte-for-byte by the -with-crypto build (crypton), this ensures hash parity in CI.

Net effect
Default builds are unchanged; script authors can opt into a C-library-free toolchain with flags: -with-crypto.

[SeungheonOh]

I assume the main goal we want to achieve is being able to compile plutus-tx-plugin and plutus-ledger-api without the crypto c libraries. While this PR does allow that, I think the cleaner way is to separate the AST definitions from plutus-core(perhaps call it plutus-ast and to make plutus-tx-plugin and plutus-ledger-api only depend on plutus-ast which does not have any c crypto dependencies(or any dependencies really).

Doing it that way would allow us to achieve same thing without requiring cabal flags which I'd prefer.

Update:
Okay, seems like this approach is already been tried and is more difficult than I originally anticipated.

[SeungheonOh]

I'd rather not have this duplicate validation logic that's originally in the blst c library. \_ _ -> Left (CryptoDisabled :: BLS12_381_Error) would be sufficient