Feature/add table export as capability (#242)

* added table export as a table capability

* fixed missing import

* fix removing capability, which was enum, rather than a string

Author: tim-chamberlain

qqq-backend-core/src/main/java/com/kingsrook/qqq/backend/core/model/metadata/frontend/QFrontendTableMetaData.java

@@ -250,7 +250,9 @@ public QFrontendTableMetaData withoutCapability(Capability capability)
       {
          this.capabilities = new HashSet<>();
       }
-      this.capabilities.remove(capability);
+
+      this.capabilities.remove(capability.toString());
+
       return (this);
    }