[Draft] Universal Marlowe Script: combine Validator and MintingPolicy in a single script

[nau]

PoC of an idea to combine validator and mintingPolicy in a single script.

It's possible to produce a script that can be run in both Validation and Minting contexts.
In such a case we can mint Marlowe role tokens and ensure we created a Marlowe contract that uses these tokens within the same transaction. Thus, we can guarantee that no one can reuse the same tokens for different Marlowe contracts produced this way.

The thing is that tokens' CurrencySymbol == ValidatorHash, and we can check during minting that the Tx contains a script TxOut with ValidatorHash == CurrencySymbol.

[bwbush]

@palas, the SCP-4107 assessment for this PR was formulated as a Marlowe Improvement Proposal (MIP): marlowe-lang/MIPs#1.

[bwbush]

Language.Marlowe.Scripts from this PR has been cherry-picked, modified, and merged into https://github.com/input-output-hk/marlowe-cardano/tree/SCP-4107, which is derived from https://github.com/input-output-hk/marlowe-cardano/tree/sprint-61.

[bwbush]

Consideration of the universal validator has been moved to marlowe-lang/MIPs#1.