feat: improve the LDAP implementation (#615)

* feat(logging): add PV_LOG_LEVEL environment variable to set backend log level

* feat(ldap): Adding a more verbose logging output to debug LDAP issues

* fix(ldap): fixed user logins with special characters within the users dn by switching to ldapts

* feat(ldap): made the member of and email attribute names configurable

* fix(ldap): properly handle email like usernames and fixing #601

* Revert "fix: disable email login if ldap is enabled"

This reverts commit d9cfe697d6.

* feat(ldap): disable the ability for a user to change his email when it's a LDAP user

* feat(ldap): relaxed username pattern by allowing the @ character in usernames

frontend/src/components/auth/SignInForm.tsx

@@ -80,9 +80,7 @@ const SignInForm = ({ redirectPath }: { redirectPath: string }) => {
     useState(false);
 
   const validationSchema = yup.object().shape({
-    emailOrUsername: config.get("ldap.enabled")
-      ? yup.string().matches(/^[^@]+$/, t("signIn.error.invalid-username"))
-      : yup.string().required(t("common.error.field-required")),
+    emailOrUsername: yup.string().required(t("common.error.field-required")),
     password: yup
       .string()
       .min(8, t("common.error.too-short", { length: 8 }))
@@ -174,16 +172,8 @@ const SignInForm = ({ redirectPath }: { redirectPath: string }) => {
             })}
           >
             <TextInput
-              label={
-                config.get("ldap.enabled")
-                  ? t("signup.input.username")
-                  : t("signin.input.email-or-username")
-              }
-              placeholder={
-                config.get("ldap.enabled")
-                  ? t("signup.input.username.placeholder")
-                  : t("signin.input.email-or-username.placeholder")
-              }
+              label={t("signin.input.email-or-username")}
+              placeholder={t("signin.input.email-or-username.placeholder")}
               {...form.getInputProps("emailOrUsername")}
             />
             <PasswordInput