Allow reference ABI types in dynamic ABI types

[ErikHasselwander]

Problem

Right now it's not possible to have a dynamic array of reference types. A current workaround for this is to instead of reference types use their non-reference counterparts (uint64 for app, asset and address for Account). This is however not good enough as it requires workarounds in the SDKs to get the foreign references included which breakes the ease of use of the ATC/ABI.

Solution

Update pyteal to support dynamic reference types.

Urgency

It is currently hindering us from deploying production ready apps without some heavy workaround in the SDKs. It would be very nice to see this fixed.

[StylishTriangles]

Same issue here, would be nice to have this added