Allow off-chain indetermisim

[athei]

The Vision

Some users want to use contracts for number crunching (floats are banned cause of in-determinism) in off-chain situations. In these cases determinism is not required because the results are not subject to consensus.

In this case the requirement comes from the phala team who runs the contract in a secure enclave (off-chain) and wants allow users to to computation there.

The Plan

We allow for the upload of in-deterministic code blobs but prevent users from using them on-chain. Only when called off-chain (through bare_call with a specific flag) we allow the execution. Please note that those code blobs can never be instantiated into a contract cause that would require on-chain execution. The only way to use them is from another contract using seal_delegate_call. A code will be flagged in-deterministic on upload by adding a new dispatchable exactly for this reason. We don't change the existing upload_code for backwards compatibility reasons.

Original discussion: #11367

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