Add functionality to update password with password hash (#15343)

* Add functionality to update password with password hash

This can be used to update a user's password with a direct password
hash instead of providing the password in plaintext.

* Use test helper for local mode

go.mod

@@ -85,7 +85,7 @@ require (
 	github.com/remyoudompheng/bigfft v0.0.0-20190728182440-6a916e37a237 // indirect
 	github.com/rs/cors v1.7.0
 	github.com/rudderlabs/analytics-go v3.2.1+incompatible
-	github.com/russellhaering/goxmldsig v0.0.0-20180430223755-7acd5e4a6ef7 // indirect
+	github.com/russellhaering/goxmldsig v0.0.0-20180430223755-7acd5e4a6ef7
 	github.com/rwcarlsen/goexif v0.0.0-20190401172101-9e8deecbddbd
 	github.com/segmentio/backo-go v0.0.0-20200129164019-23eae7c10bd3 // indirect
 	github.com/sirupsen/logrus v1.6.0
@@ -108,14 +108,11 @@ require (
 	github.com/wiggin77/merror v1.0.2
 	github.com/wiggin77/srslog v1.0.1
 	github.com/xtgo/uuid v0.0.0-20140804021211-a0b114877d4c // indirect
-	github.com/ziutek/mymysql v1.5.4 // indirect
-	github.com/zmb3/gogetdoc v0.0.0-20190228002656-b37376c5da6a // indirect
 	go.etcd.io/bbolt v1.3.5 // indirect
 	go.uber.org/zap v1.15.0
 	golang.org/x/crypto v0.0.0-20200728195943-123391ffb6de
 	golang.org/x/image v0.0.0-20200618115811-c13761719519
 	golang.org/x/lint v0.0.0-20200302205851-738671d3881b // indirect
-	golang.org/x/mod v0.3.0 // indirect
 	golang.org/x/net v0.0.0-20200707034311-ab3426394381
 	golang.org/x/sys v0.0.0-20200805065543-0cf7623e9dbd // indirect
 	golang.org/x/text v0.3.3