Checkpoint Syslog Filebeat module (#17682)

This adds a CheckPoint Filebeat module.

The difference between this module and the CEF checkpoint module is that this is utilizing the syslog output format instead of CEF.

This syslog output format supports a much larger set of fields from Checkpoint.

(cherry picked from commit afc3a49)

Author: P1llus

CHANGELOG.next.asciidoc

@@ -328,6 +328,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Improve ECS categorization field mappings for mysql module. {issue}16172[16172] {pull}17491[17491]
 - Release Google Cloud module as GA. {pull}17511[17511]
 - Update filebeat httpjson input to support pagination via Header and Okta module. {pull}16354[16354]
+- Added new Checkpoint Syslog filebeat module. {pull}17682[17682]
 - Enhance `elasticsearch/server` fileset to handle ECS-compatible logs emitted by Elasticsearch. {issue}17715[17715] {pull}17714[17714]
 
 *Heartbeat*