Change log for PROOFPOINT_MAIL

Date	Changes
2023-06-26	Enhancement - - Mapped "clicks.threatStatus" to "security_result.threat_status".
2022-11-03	Enhancement - Added condition check for date field . "give the higher priority to the date which has maximum timestamp". if "click_time" > "threat_time" date mapped to click_time else threat_time.
2022-07-13	Enhancement - Modified the mapping for "intermediary.user.email_addresses" from "(messagesBlocked|messagesDelivered).*toAddresses" to "(messagesBlocked|messagesDelivered).*ccAddresses" .
2022-06-29	Enhancement - Added gsub to remove '<>' from the fields 'clicks.messageID' and 'm' mapped to 'network.email.mail_id'.
2022-05-25	Mapped "messageSize" to "additional" field. Mapped "campaignID" to "security_result.rule_id" field. Mapped "ccAddresses" to "intermediary.user.email_addresses" field. Mapped "toAddresses" to "target.user.email_addresses" field.