Refactor password validation and config defaults (#7859)

* refactor password validation and config defaults

* reorder config lines for clarity

app/authentication.go

@@ -11,6 +11,13 @@ import (
 	"github.com/mattermost/mattermost-server/utils"
 )
 
+func (a *App) IsPasswordValid(password string) *model.AppError {
+	if utils.IsLicensed() && *utils.License().Features.PasswordRequirements {
+		return utils.IsPasswordValidWithSettings(password, &a.Config().PasswordSettings)
+	}
+	return utils.IsPasswordValid(password)
+}
+
 func (a *App) CheckPasswordAndAllCriteria(user *model.User, password string, mfaToken string) *model.AppError {
 	if err := a.CheckUserAdditionalAuthenticationCriteria(user, mfaToken); err != nil {
 		return err

app/user.go

@@ -213,7 +213,7 @@ func (a *App) CreateUser(user *model.User) (*model.User, *model.AppError) {
 func (a *App) createUser(user *model.User) (*model.User, *model.AppError) {
 	user.MakeNonNil()
 
-	if err := utils.IsPasswordValid(user.Password); user.AuthService == "" && err != nil {
+	if err := a.IsPasswordValid(user.Password); user.AuthService == "" && err != nil {
 		return nil, err
 	}
 
@@ -1086,7 +1086,7 @@ func (a *App) UpdatePasswordByUserIdSendEmail(userId, newPassword, method string
 }
 
 func (a *App) UpdatePassword(user *model.User, newPassword string) *model.AppError {
-	if err := utils.IsPasswordValid(newPassword); err != nil {
+	if err := a.IsPasswordValid(newPassword); err != nil {
 		return err
 	}