Add anonymizeIP to GA privacy config

See #4751

config/privacy/privacyConfig.go

@@ -48,6 +48,9 @@ type GoogleAnalytics struct {
 	// Enabling this will make the GA templates respect the
 	// "Do Not Track" HTTP header. See  https://www.paulfurley.com/google-analytics-dnt/.
 	RespectDoNotTrack bool
+
+	// Enabling this will make it so the users' IP addresses are anonymized within Google Analytics.
+	AnonymizeIP bool
 }
 
 // Instagram holds the privacy configuration settings related to the Instagram shortcode.

config/privacy/privacyConfig_test.go

@@ -34,6 +34,7 @@ disable = true
 [privacy.googleAnalytics]
 disable = true
 respectDoNotTrack = true
+anonymizeIP = true
 [privacy.instagram]
 disable = true
 simple = true
@@ -59,6 +60,7 @@ simple = true
 	assert.True(pc.Disqus.Disable)
 	assert.True(pc.GoogleAnalytics.Disable)
 	assert.True(pc.GoogleAnalytics.RespectDoNotTrack)
+	assert.True(pc.GoogleAnalytics.AnonymizeIP)
 	assert.True(pc.Instagram.Disable)
 	assert.True(pc.Instagram.Simple)
 	assert.True(pc.SpeakerDeck.Disable)