Feat #1700: Add values_wo write-only attribute for ephemeral resource support in values

[dennismdejong]

Adds values_wo (write-only list of YAML strings) and values_wo_revision (counter) attributes to helm_release, analogous to existing set_wo/set_wo_revision.

• values_wo is a ListAttribute with WriteOnly: true — values are not persisted in state/plan
• values_wo_revision integer counter — incrementing triggers an update
• Merged into chart values during Create/Update (same pattern as set_wo)
• Read skips writing merged values to metadata when values_wo_revision > 0