Change log for ZSCALER_DNS

Date Changes
2024-10-23 Enhancement:
- Added support to parse unparsed JSON logs.
2024-05-28 Enhancement:
- Mapped "dns_reqtype" to "additional.fields".
2024-05-10 Enhancement:
- Mapped "dns_resp" to "event.idm.read_only_udm.network.dns.answers.data".
- Mapped "event1.durationms" to "network.session_duration.seconds".
- Mapped "event1.location" to "additional.fields".
- Mapped "event1.category" and "event1.respipcategory" to "sec_result.category_details".
2023-10-17 Enhancement -
- Written a Grok pattern to parse the log of CSV format.
- Dropped the logs that do not match any Grok pattern.
2022-09-30 Enhancement -
- Parsed Json format logs.
- Dropped Encoded logs.