PLT-4332 Position field for Users (#4632)

* Add User.Position field to store & model.

* GOFMT

* Add Position to user settings.

* Unit tests.

* Add position to profile popup.

* i18n

* Fix log message for invalid position.

* Add Position field attribute to LDAP config.

* Add Position field attribute to SAML config.

* Reword empty position message.

* Change Position Max Length to 35.

* Better invalid position error message.

* Add new fields to config.json.

* Ensure position is never longer than max when displayed.

* Hard limit of 64 chars with soft limit still 35

* Put field with other attributes.

model/user_test.go

@@ -128,6 +128,17 @@ func TestUserIsValid(t *testing.T) {
 	if err := user.IsValid(); err == nil {
 		t.Fatal(err)
 	}
+
+	user.LastName = ""
+	user.Position = ""
+	if err := user.IsValid(); err != nil {
+		t.Fatal(err)
+	}
+
+	user.Position = strings.Repeat("01234567890", 20)
+	if err := user.IsValid(); err == nil {
+		t.Fatal(err)
+	}
 }
 
 func TestUserGetFullName(t *testing.T) {