remove "stripEmailDomain" argument

This commit makes a wrapper function round the normalisation requiring
"stripEmailDomain" which has to be passed in almost all functions of
headscale by loading it from Viper instead.

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

hscontrol/util/dns.go

@@ -7,6 +7,7 @@ import (
 	"regexp"
 	"strings"
 
+	"github.com/spf13/viper"
 	"go4.org/netipx"
 	"tailscale.com/util/dnsname"
 )
@@ -24,6 +25,12 @@ var invalidCharsInUserRegex = regexp.MustCompile("[^a-z0-9-.]+")
 
 var ErrInvalidUserName = errors.New("invalid user name")
 
+func NormalizeToFQDNRulesConfigFromViper(name string) (string, error) {
+	strip := viper.GetBool("oidc.strip_email_domain")
+
+	return NormalizeToFQDNRules(name, strip)
+}
+
 // NormalizeToFQDNRules will replace forbidden chars in user
 // it can also return an error if the user doesn't respect RFC 952 and 1123.
 func NormalizeToFQDNRules(name string, stripEmailDomain bool) (string, error) {