feat(nns): Post-process potentially large fields in NnsCanisterInstall/HardResetRootToVersion SelfDescribingValue

[jasonz-dfinity]

Post-process potentially large fields in NnsCanisterInstall/HardResetRootToVersion SelfDescribingValue. Note that this treatment is highly consistent with InstallCode - only the hashes are returned, with the field names as *_hash instead of *.

[github-actions]

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