ABI: Support reference types (account, asset, and application)

[michaeldiamant]

Problem

https://github.com/algorandfoundation/ARCs/blob/main/ARCs/arc-0004.md#reference-types defines reference types accessible via foreign arrays on the AVM. To close the PyTeal ABI support gap, the ticket requests:

• Defining ARC-4 Applications with methods containing reference type parameters.
• Calling methods of ARC-4 Applications with reference type arguments.

Solution

TBD - Consider the state of PyTeal when picking up the effort. Consider if #254 ought to be done in tandem.

Dependencies

• ABI: Defining an ARC-4 Application #185
• TBD ticket for calling ARC-4 Applications.

Urgency

TBD

[barnjamin]

#343 added something to start experimenting with this

[jasonpaulos]

Completed by #361