Add Referrer field to AuditEntry

[ngoduykhanh]

Fix#3031

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (fb8a83d) 97.91% compared to head (27a2fa0) 97.91%.
Report is 1 commits behind head on master.

Additional details and impacted files

@@ Coverage Diff @@## master #3032 +/- ##
=======================================
Coverage 97.91% 97.91% =======================================
Files 150 150 Lines 12980 12980 =======================================
Hits 12710 12710 Misses 192 192 Partials 78 78 

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[gmlewis]

Thank you, @ngoduykhanh !
LGTM.
Merging.