PyCardano does not correctly load nested PlutusData from cbor where the keys are unions of PlutusData

[nielstron]

Describe the bug
When trying to load a ScriptContext from a CBOR description of it, the data is not correctly unwrapped.
The issue is that the redeemers dict is a dict from Redeemer to PlutusDatum, where Redeemer is a Union of PlutusData objects. Currently, only direct PlutusData objects are unrolled but not recursively defined container and union types.

To Reproduce

from opshin.prelude import ScriptContext
x = ScriptContext.from_cbor("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")
# only here the script fails as it finds weird ConstrData remainders
x.to_json()