feat!: make AES128 decrypt oracle return Option (backport #21696)

[AztecBot]

Summary

Backport of #21696 to v4-next.

• Rename AES128 decrypt oracle from aztec_utl_aes128Decrypt to aztec_utl_tryAes128Decrypt, returning Option<BoundedVec<u8, N>> instead of BoundedVec<u8, N>
• Wrap TS decrypt calls (PXE + TXE) in try/catch so Barretenberg exceptions on malformed input return Option::none() instead of crashing the process
• Remove legacy utilityAes128Decrypt mapping
• Bump oracle version to 19 and update oracle interface hash

Conflicts resolved

Cherry-pick conflicted in oracle_version.ts and version.nr due to oracle version bump from merged sync cache invalidation oracle PR. Resolved by bumping to version 19 and regenerating the interface hash.

Test plan

• CI passes (Noir compile + TS build)
• AES128 decrypt tests pass with new Option return type