feat: integrate reference scripts

[scarmuega]

Context

Preferred method for including scripts in txs is via reference scripts. The location of these scripts is defined by the reference of the UTxO that holds them. This introduces some challenges:

• these reference are chain / network specific, so it's not straightforward how to map that into network-agnostic syntax
• defining these utxos is usually a protocol-author concern and not a tx-builder concern, so passing the location of the utxos at runtime is inefficient

DoD

• we have a recommended approach for including reference scripts in tx3 templates
• we have documentation to explain the approach
• we have working example
• we have a language-level integration test