[AIRFLOW-5672][WIP] Rename CloudDLPHook to CloudDlpHook

[michalslowikowski00]

Part of AIP-21

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[mik-laj]

If we use shortcuts, we should write them Capitalized e.g. GKE, GCS

https://docs.google.com/document/d/1_rTdJSLCt0eyrAylmmgYc3yZr-_h51fVlnvMmWqhCkY/edit?ts=5bb72dfd#

We need to update our planned changes

[mik-laj]

Can you also update a note in UPDATING.md file?
https://github.com/apache/airflow/blob/master/UPDATING.md#changes-to-import-paths-and-names-of-gcp-operators-and-hooks

[michalslowikowski00]

@mik-laj Should we leave CloudDLPHooka and follow the this rules?https://docs.google.com/document/d/1_rTdJSLCt0eyrAylmmgYc3yZr-_h51fVlnvMmWqhCkY/edit?ts=5bb72dfd#