try to render some changes between "" and null

[jbardin]

Changes between empty strings and null were hidden in the CLI output, because the SDK could not reliably detect the difference and may return either value depending on the situation.

This legacy behavior can be confusing for authors of new providers which can correctly handle null, and it would be preferable to be able to render those changes in the CLI.

While we don't have enough information to detect when the legacy behavior is required, we can detect a number of cases where it's certain that we are not dealing with a legacy schema and should output the full diff:

• Anything with nested structural attributes
• Blocks of type NestingMap and NestingGroup
• Dynamic types

While this cannot solve all issues when the resource only uses primitive types, like with random_password in #31887, it would for example solve the terraform_data example because of it's use of DynamicPseudoType.

[bflad]

I don't have full context on the implications of this sort of change, but from the proposed changes here, it feels like a relatively lightweight enough and pragmatic way to help the renderer in this situation without going the full route of encoding the "legacy type system" flag into the plan. We can always back this change out if there are concerns or issues. All the code is internal and it only affects the human-readable plan output, not the machine-readable plan output that has compatibility concerns.

[github-actions]

Reminder for the merging maintainer: if this is a user-visible change, please update the changelog on the appropriate release branch.

[github-actions]

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