Add custom dependencies to built-in HelmReleases

Summary

• Add a shared dependsOn contract for built-in package configuration.
• Append user-supplied dependencies to existing generated dependencies for all 44 built-in HelmReleases.
• Use the shared renderer for generic and wrapped custom packages.
• Preserve legacy and packageConfiguration.version: v1 configuration paths.
• Document the common dependency configuration and add focused schema/rendering tests.

Validation

• helm lint ./chart
• scripts/generate-package-schemas.sh --check
• All 44 built-in HelmRelease templates rendered with an additional dependency.
• Legacy, unified packages.*, and wrapped custom-package paths rendered successfully.
• tests/bats/generate-package-schemas/generate-package-schemas.bats

Local environment notes

• helm-unittest is not installed locally; CI will run the Helm unit-test suite.
• The full Bats suite was attempted, but unrelated tests require GNU timeout, parallel, or a newer Bash than the local environment provides.

Linked Issue

Closes #3380 (closed)

Upgrade Notices

N/A - no breaking changes. The dependsOn key retains its original additive behavior. The new dependsOnOverride key is an opt-in replacement path.