Moving storage iterator into core modules.

Error was introduced in googleapis#941 mistakenly.

…mples#941)

* feat: Add BigQuery Metastore Partition Service API version v1beta

PiperOrigin-RevId: 753333720

Source-Link: googleapis/googleapis@389abd1

Source-Link: googleapis/googleapis-gen@a875887
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiYTg3NTg4NzkxYWMwMDU3YjViY2Q1YjkxZTQ5N2E1ZGFmZjY2ZWJiYyJ9

* update replacement in owlbot.py

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* Add gapic_version.py

* update gapic_version.py

* update docs/index.rst

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>
Co-authored-by: Anthonios Partheniou <partheniou@google.com>

* feat: Add BigQuery Metastore Partition Service API version v1beta

PiperOrigin-RevId: 753333720

Source-Link: googleapis/googleapis@389abd1

Source-Link: googleapis/googleapis-gen@a875887
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiYTg3NTg4NzkxYWMwMDU3YjViY2Q1YjkxZTQ5N2E1ZGFmZjY2ZWJiYyJ9

* update replacement in owlbot.py

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* Add gapic_version.py

* update gapic_version.py

* update docs/index.rst

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>
Co-authored-by: Anthonios Partheniou <partheniou@google.com>

Generate mock field inputs for all required fields.

* For oneofs, the first option is selected.
* For enums, the last option is selected (as 0 is often unspecified).
* Mock input for string fields that reference resources (`resource_pb2.resource_reference`) is the pattern provided in the protos.

**TODOs:**
- When a resource's pattern is `*` this results in unhelpful strings
    ```proto
    message Asset {
      option (google.api.resource) = {
        type: "cloudasset.googleapis.com/Asset"
        pattern: "*"
      };
    ```

    ```py
    request = asset_v1.BatchGetAssetsHistoryRequest(
       parent="*",
    )
    ```
- Map fields are not yet handled.

**Other changes:**

* Fields are set like `foo.bar` rather than through dict access `foo["bar"]`. This is because the former allows you to set fields nested more than one field deep `foo.bar.baz`.

    **Before**:
    ```py
    output_config = {}
    output_config["gcs_destination"]["uri"] = "uri_value" # fails as there is no nested dict
    ```

    **After**:
    ```py
    output_config = asset_v1.IamPolicyAnalysisOutputConfig()
    output_config.gcs_destination.uri = "uri_value"
    ```