feat: Add reserved no-value keyword for option sets [DHIS2-21600]

[luciano-fiandesio]

Summary

Introduce D2__NOVALUE as the reserved no-value keyword for option-set analytics query dimensions, while keeping legacy NV behavior for non-option-set dimensions.

events

• Treat D2__NOVALUE as IS NULL only for option-set query items.
• Treat NV as a literal option code for option-set dimensions.
• Preserve legacy NV no-value behavior for non-option-set dimensions.
• Reject D2__NOVALUE on non-option-set dimensions with E7246.
• Append D2__NOVALUE to metaData.dimensions only when an option-set query item is explicitly filtered by it.
• Keep rows unchanged: missing option-set values still render as empty strings.

Request

dimension=ou:ImspTQPwCqd,fWIAEtYVEGk:IN:D2__NOVALUE

Response

 "metaData": {
   "dimensions": {
      "fWIAEtYVEGk": [
                "D2__NOVALUE"
            ]
   }
 }

enrollments

• Apply the same option-set-aware no-value keyword rules in enrollment query filtering.
• Thread option-set context through QueryFilter, InQueryFilter, CTE filter handling, and validation.
• Preserve CTE/null-filter semantics so no-value filters remain outside CTE filtering where required.
• Add/update tests covering D2__NOVALUE, legacy NV, mixed filters, and validation behavior.

tracked entities

• Add tracked entity query validation to reject D2__NOVALUE on non-option-set dimensions with E7246.
• Pass option-set context through the tracked entity condition renderer chain.
• Add dimensions-only metadata handling for option-set filters using D2__NOVALUE.
• Remove the reverted row relabeling/synthetic metadata item behavior.
• Ensure both normal query and explain paths apply the new validation rules.

[github-actions]

Instance deployed to https://dev.im.dhis2.org/pr-24281

[sonarqubecloud]

Quality Gate failed

Failed conditions
1 New issue
1 New Code Smells (required ≤ 0)

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