Broken by multiple deprecated options when using google provider >=4.0.0

The release of google provider 4.0.0 contained some breaking changes to the workload_identity_config and workload_metadata_config blocks in the google_container_cluster resource.

The identity_namespace option in workload_identity_config has now been replaced with workload_pool and the node_metadata option in workload_metadata_config has now been replaced with mode.

Currently we have the google provider configured to allow versions >= 3.70 which causes this module to break when using provider >= 4.0.0 due to these changes.

We'll need to adopt these new options and change the minimum supported version for the google provider to >= 4.0.0. This is obviously a breaking change so we'll also need to bump this module to major version 4 at the same time.