Add external catalog table options to google_bigquery_table beta (GoogleCloudPlatform#12528)

Author: wj-chen

mmv1/products/bigquery/Table.yaml

@@ -550,3 +550,75 @@ properties:
       in the namespaced format, for example "123456789012/environment" where 123456789012 is the
       ID of the parent organization or project resource for this tag key. Tag value is expected
       to be the short name, for example "Production".
+  - name: externalCatalogTableOptions
+    type: NestedObject
+    description: |
+      Options defining open source compatible table.
+    min_version: beta
+    properties:
+      - name: 'parameters'
+        type: KeyValuePairs
+        description: |
+          A map of key value pairs defining the parameters and properties of the open source table.
+          Corresponds with hive meta store table parameters. Maximum size of 4Mib.
+        min_version: beta
+      - name: 'storageDescriptor'
+        type: NestedObject
+        description: |
+          A storage descriptor containing information about the physical storage of this table.
+        min_version: beta
+        properties:
+          - name: 'storageUri'
+            type: String
+            description: |
+              The physical location of the table (e.g. `gs://spark-dataproc-data/pangea-data/case_sensitive/`
+              or `gs://spark-dataproc-data/pangea-data/*`). The maximum length is 2056 bytes.
+            min_version: beta
+          - name: 'inputFormat'
+            type: String
+            description: |
+              Specifies the fully qualified class name of the InputFormat
+              (e.g. "org.apache.hadoop.hive.ql.io.orc.OrcInputFormat").
+              The maximum length is 128 characters.
+            min_version: beta
+          - name: 'outputFormat'
+            type: String
+            description: |
+              Specifies the fully qualified class name of the OutputFormat
+              (e.g. "org.apache.hadoop.hive.ql.io.orc.OrcOutputFormat").
+              The maximum length is 128 characters.
+            min_version: beta
+          - name: 'serdeInfo'
+            type: NestedObject
+            description: |
+              Serializer and deserializer information.
+            min_version: beta
+            properties:
+              - name: 'name'
+                type: String
+                description: |
+                  Name of the SerDe. The maximum length is 256 characters.
+                min_version: beta
+              - name: 'serializationLibrary'
+                type: String
+                description: |
+                  Specifies a fully-qualified class name of the serialization library that is
+                  responsible for the translation of data between table representation and the
+                  underlying low-level input and output format structures.
+                  The maximum length is 256 characters.
+                required: true
+                min_version: beta
+              - name: 'parameters'
+                type: KeyValuePairs
+                description: |
+                  Key-value pairs that define the initialization parameters for the serialization
+                  library. Maximum size 10 Kib.
+                min_version: beta
+      - name: 'connectionId'
+        type: String
+        description: |
+          The connection specifying the credentials to be used to read external storage, such as
+          Azure Blob, Cloud Storage, or S3. The connection is needed to read the open source table
+          from BigQuery Engine. The connection_id can have the form `<project_id>.<location_id>.<connection_id>`
+          or `projects/<project_id>/locations/<location_id>/connections/<connection_id>`.
+        min_version: beta