Git authentications should be stored in audit events

Zendesk issue: https://gitlab.zendesk.com/agent/tickets/15751

Should Git over HTTPS and SSH logins be recorded in audit events?

cc/ @JobV @DouweM

Added gitlab-org/gitlab-ce~113220 label

Added gitlab-org/gitlab-ce~14213 label

Yeah, makes sense to me.

Milestone changed to 8.7

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Removed ~155950 label

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Milestone changed to 8.8

Moved from gitlab-org/gitlab-ce#13567

Added repository audit events ~113221 feature proposal labels

Milestone changed to 8.8

mentioned in issue #579

Milestone changed to Backlog

Somewhat linked to https://gitlab.com/gitlab-org/gitlab-ee/issues/68

Mentioned in issue #1022 (closed)