Change log for IMPERVA_WAF

Date Changes
2022-05-10 Enhancement - Mapped the following fields:
- 'cs1', 'cs2', 'cs3', 'cs4', 'cs5', 'fileType', 'filePermission' to 'security_result.detection_fields'.
- 'cs7' to 'principal.location.region_latitude'.
- 'cs8' to 'principal.location.region_longitude'.
- 'cn1', 'cn2' to 'security_result.detection_fields' for CEF format logs.
- 'act' to 'security_result.action' and 'security_result.action_details' for CEF format logs.
- 'app' to 'network.application_protocol' for CEF format logs.
- 'requestClientApplication' to 'network.http.user_agent' for CEF format logs.
- 'dvc' to 'about.ip' for CEF format logs.