Allow overrides of the name identifier and additional labels on the GCP instance.

right now for creating multiple postgres clusters using the GET GCP module we have have prefix and node_type.

• node_type should be set to postgres for a postgres host.
• The combination of prefix-node_type must be unique within a project

This means that we need to currently include the shard identifier in prefix.

For example: with two shards main and ci we will generate name identifiers like production-main-postgres-1, produciton-ci-postgres-1

However, naming conventions in infrastructure should increase in specificity from left to right, for this we want

production-postgres-main-1, production-postgres-ci-1

Without introducing the concept of "shard" to the module, I am proposing here that we allow a name_id override, that will allow you set your own identifier (where the default remains the same).

This also allows us to pass in additional instance labels, so we can label our instances with shard.