For #11892 - Pass ParsedStructure as bytearray instead of as parcelable

[Mugurell]

This avoids the system trying to remap our ParsedStructure parcelable failing
by not using the right ClassLoader.

Implementing Parcelable on our own was needed to be able to manually create
ParsedStructure from the unmarshalled parcel.

Passing out ClassLoader in the intent (as the recommended approach) did not work.

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[Amejia481]

This looks good!
Is possible to create tests to simulate the crash and ensure we are not regressing in the future?

[Mugurell]

This looks good! Is possible to create tests to simulate the crash and ensure we are not regressing in the future?

Managed to somehow add a test for the parcelable code but it seems most of the platform functionality is private, hard to peek into or test from outside.
Looked into testing that the FillResponse constructed when the user has to first log in contains the expected parcelable or that AbstractAutofillUnlockActivity does indeed recreate the expected object from the parcel but FieldResponse does not want to cooperate.
Not sure how to refactor the code to make it more easily testable and given the complexity I probably shouldn't.