Add rill sudo project dump-instances

[begelundmuller]

Adds rill sudo project dump-instances [<project-pattern>], a sibling of dump-resources that calls GetInstance on each matching project's runtime and dumps the result as JSON.

• Useful for auditing values that are spread across runtimes, such as feature_flags, olap_connector, annotations and ai_connector.
• Keys use the proto field names (feature_flags, not featureFlags), and each row is annotated with org, project and runtime_host.
• Sensitive values (connector configs and variables) are only included with --sensitive, which requires ReadInstance on the issued superuser token.
• Projects without a deployment are skipped; per-project failures are reported at the end instead of aborting the run.