Add email field to user and match users by email

Author: Thomasr

server/api-service/lowcoder-server/src/main/java/org/lowcoder/api/authentication/util/AuthenticationUtils.java

@@ -112,6 +112,7 @@ public static AuthUser mergeAuthUser(AuthUser low, AuthUser high) {
         return AuthUser.builder()
                 .uid(high.getUid() != null ? high.getUid() : low.getUid())
                 .username(high.getUsername() != null ? high.getUsername() : low.getUsername())
+                .email(high.getEmail() != null ? high.getEmail() : low.getEmail())
                 .avatar(high.getAvatar() != null ? high.getAvatar() : low.getAvatar())
                 .rawUserInfo(high.getRawUserInfo() != null ? high.getRawUserInfo() : low.getRawUserInfo())
                 .authToken(high.getAuthToken() != null ? high.getAuthToken() : low.getAuthToken())