Typo in Google Cloud Storage sensor: airflow/providers/google/cloud/sensors/gcs/GCSObjectsWithPrefixExistenceSensor

The word _With_ is spelled incorrectly. It should be: GCSObjects**With**PrefixExistenceSensor

**Apache Airflow version**: 2.0.0
**Environment**:
- **Cloud provider or hardware configuration**: Google Cloud
- **OS** (e.g. from /etc/os-release): Mac OS BigSur






tests/always/test_project_structure.py
MISSING_EXAMPLE_DAGS = {
        ('cloud', 'adls_to_gcs'),
        ('cloud', 'sql_to_gcs'),
        ('cloud', 'bigquery_to_mysql'),
        ('cloud', 'cassandra_to_gcs'),
        ('cloud', 'mssql_to_gcs'),
        ('suite', 'drive'),
        ('ads', 'ads_to_gcs'),
    }
    MISSING_EXAMPLES_FOR_OPERATORS = {
        
        'airflow.providers.google.cloud.operators.cloud_storage_transfer_service'
        '.CloudDataTransferServiceS3ToGCSOperator',
        
        'airflow.providers.google.cloud.operators.cloud_storage_transfer_service'
        '.CloudDataTransferServiceGCSToGCSOperator',
        
        'airflow.providers.google.cloud.operators.cloud_sql.CloudSQLBaseOperator',
        
        'airflow.providers.google.cloud.operators.dataproc.DataprocSubmitHadoopJobOperator',
        'airflow.providers.google.cloud.operators.dataproc.DataprocInstantiateInlineWorkflowTemplateOperator',
        
        'airflow.providers.google.cloud.operators.dataproc.DataprocScaleClusterOperator',
        
        'airflow.providers.google.cloud.operators.dataproc.DataprocJobBaseOperator',