Log current IP address of request that tries to access an IP restricted group

What does this MR do?

Logs the IP Address of incoming request to access an IP restricted group. Also log the group's path and whether the access was granted.

This will help with debugging issues such as #39093 (closed)

Related slack conversation: https://gitlab.slack.com/archives/CBQ76ND6W/p1575876579006700

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
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Security

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• Label as security and @ mention @gitlab-com/gl-security/appsec
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