Enhance precomputed block tests with more datapoints

[georgeee]

Preliminary Checks

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Summary

Precomputed blocks are exported in json format, but the existing JSON serialization test doesn't cover all of the types included in the block.

Namely the following important data structures are completely absent from the test coverage:

• Zkapp transactions
• Completed works

This introduces a risk of accidentally changing JSON serialization format (without changing the bin_io serialization) that will be uncaught.
We need to enhance tests to be able to capture this case.

Steps to replicate this Issue

Merging this PR would cause troubles:

• Use Proof_carrying_data in Transaction_snark.t #16479

A Mina node running this PR would produce precomputed blocks of a format that is incompatible with the existing Mina node code

Console output

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Platform

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Build link(s)

No response