ERA-66338: Add MongoDB HA (ReplicaSet) instance support

[sasikanthmasini]

What this PR does / why we need it

This PR implements PR #244 — adds support for MongoDB HA (ReplicaSet) via the NDB Operator.

Changes

API (api/v1alpha1)

• database_types.go: Added MongoHAConfig struct with ReplicaSetName, ReplicaSetDescription, DeployArbiter, ArbiterComputeProfileId, and ListenerPort fields. Added MongoDB *MongoHAConfig to InstanceHAConfig. Extended nodeType enum with "arbiter".
• ha_validators.go: Added MongoHAParamsValidator for webhook validation of MongoDB HA constraints (required mongodb config block, exactly one primary, arbiter consistency with deployArbiter, node type restrictions).
• zz_generated.deepcopy.go: Added generated DeepCopy/DeepCopyInto for MongoHAConfig.

Common

• constants.go: Added HA_MONGO_DEFAULT_LISTENER_PORT, HA_NODE_TYPE_ARBITER, HA_NODE_ROLE_MONGO_PRIMARY/SECONDARY/ARBITER constants.
• common/util/additionalArguments.go: Allowed cluster_name and cluster_description as overridable MongoDB HA action arguments.

NDB API (ndb_api)

• interfaces.go: Added IsMongoHA() to DatabaseInterface and MongoDB-specific fields (ReplicaSetName, DeployArbiter, ArbiterComputeProfileId, MongoListenerPort) to HAConfig.
• db_helpers.go: Added MongoDB HA provisioning request block (clustered=true, per-node properties with role/votes/priority, SLA cluster IDs). Updated MongoDbRequestAppender with HA-specific action arguments and changed default db_user from admin to mongod.

Controller Adapters

• controller_adapters/database.go: Added IsMongoHA() method and wired MongoDB fields in GetInstanceHAConfig().

Controllers

• controllers/ha_connectivity.go: Added MongoHAIPResolver (returns IPs of all data nodes, excludes arbiters) and MongoHAConnectivityManager (returns nil additional services — MongoDB HA uses a URI secret instead of K8s Services).
• controllers/database_reconciler_helpers.go: Added setupMongoHAConnectivity (creates a headless Service + Endpoints per data node for CoreDNS resolution, then creates/updates a <db>-db-uri Secret with the MongoDB connection URI) and setupMongoHeadlessService.
• controllers/database_controller.go: Updated RBAC annotation for secrets to include create;update;patch.

Config

• config/crd/bases/ndb.nutanix.com_databases.yaml: Added mongodb block and arbiter to nodeType enum.
• config/rbac/role.yaml: Added create, patch, update verbs for secrets.

Dependencies

• Updated go.mod/go.sum with minor dependency bumps.

How it works

MongoDB HA uses a Replica Set topology where:

• Primary node receives write/read traffic
• Secondary nodes handle read traffic and async replication
• Arbiter (optional) participates only in elections, holds no data

The operator creates:

1. A headless Kubernetes Service + Endpoints per data node so CoreDNS resolves each VM hostname to its IP (required by MongoDB SDAM for topology discovery and automatic failover)
2. A <database-name>-db-uri Secret containing the full MongoDB connection URI: mongodb://user:pass@vm1:27017,vm2:27017/dbname?replicaSet=rs0&authSource=admin

Applications use this URI with a MongoDB driver that handles routing and automatic failover via SDAM.

Tests

• TestMongoHAParamsValidator_Validate — 11 subtests covering all validation scenarios
• TestMongoHAConnectivityManager_* — registry, PrimaryPort, AdditionalServices
• TestMongoHAIPResolver_* — registry, ResolveIPs (excludes arbiters, handles empty nodes)
• Updated existing MongoDB provisioning tests with IsMongoHA mock and corrected db_user value