Made possible updating security for user groups on tables

lib/models/table_access.dart

@@ -0,0 +1,24 @@
+enum TableAccess {
+  read("r"),
+  write("w"),
+  readWrite("rw"),
+  none("");
+
+  final String def;
+
+  const TableAccess(this.def);
+
+  static TableAccess fromString(String? def) {
+    switch (def) {
+      case "r":
+        return TableAccess.read;
+      case "w":
+        return TableAccess.write;
+      case "rw":
+        return TableAccess.readWrite;
+      case "none":
+      default:
+        return TableAccess.none;
+    }
+  }
+}