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.go

@@ -37,6 +37,7 @@ type User struct {
 	Nickname           string    `json:"nickname"`
 	FirstName          string    `json:"first_name"`
 	LastName           string    `json:"last_name"`
+	Position           string    `json:"position"`
 	Roles              string    `json:"roles"`
 	AllowMarketing     bool      `json:"allow_marketing,omitempty"`
 	Props              StringMap `json:"props,omitempty"`
@@ -78,6 +79,10 @@ func (u *User) IsValid() *AppError {
 		return NewLocAppError("User.IsValid", "model.user.is_valid.nickname.app_error", nil, "user_id="+u.Id)
 	}
 
+	if utf8.RuneCountInString(u.Position) > 35 {
+		return NewLocAppError("User.IsValid", "model.user.is_valid.position.app_error", nil, "user_id="+u.Id)
+	}
+
 	if utf8.RuneCountInString(u.FirstName) > 64 {
 		return NewLocAppError("User.IsValid", "model.user.is_valid.first_name.app_error", nil, "user_id="+u.Id)
 	}