Add missing methods for API level 720

[KrzysFR]

A quick look at the current documentation for 7.2 shows that the following native methods are not implemented currently:

• [x] fdb_add_network_thread_completion_hook
• [x] fdb_future_get_key_array
• [x] fdb_database_open_tenant
• [x] fdb_database_reboot_worker
• [x] fdb_database_force_recovery_with_data_loss
• [x] fdb_database_create_snapshot
• [x] fdb_database_get_main_thread_busyness
• [x] fdb_tenant_destroy
• [x] fdb_tenant_create_transaction
• [x] fdb_transaction_get_estimated_range_size_bytes
• [x] fdb_transaction_get_range_split_points
• [x] fdb_error_predicate

These should be added and exposed in the public API.

The new Tenant API needs probably some special handling because it seems to obsolete the previous solution of using top-level partition with the Directory Layer.

[KrzysFR]

All of these methods are implemented and exposed to .NET app.