Fix #829, #805: Defer manifest computation to apply time when values contain unknown plan-time references

[dennismdejong]

Fixes #829 and #805.

Changes

1. Add warning diagnostic when manifest is deferred: When the manifest experiment is enabled and values contain unresolvable plan-time references, a warning is now emitted explaining that the manifest attribute will be computed during apply.

2. Fix valuesUnknown function:

   • Added check for individual values elements being unknown (not just the whole list)
   • Fixed copy-paste bug where SetList was reading from plan.Set instead of plan.SetList, and used the wrong model type (setResourceModel instead of set_listResourceModel)
   • Added check for individual elements within SetList values being unknown

Root cause

When the manifest experiment renders at plan time, the Helm SDK\u2019s lookup function mock can return different data at plan vs apply time. This causes a mismatch between the planned manifest and the actual manifest, resulting in the inconsistent final plan error. By deferring manifest computation to apply time when values are unknown, we avoid this issue entirely.