Implement basic static DSL for constraints

[uhbif19]

TODO:

• [ ] Write docs on design considerations of this design
• [ ] Separate validation from constraints generation in CEMScript
• [ ] Create constraints DSL datatype
• [ ] Implement DSL on- and off-chain translation
• [ ] Encode constraints using DMap

Blocked by #29

[github-actions[bot]]

Status: Ready to merge :heavy_check_mark:

Issues blocking this PR:

• 29 :heavy_check_mark:

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