Adjust namespace select filter option sizes

Signed-off-by: Alex Andreev <alex.andreev.email@gmail.com>

src/renderer/components/+namespaces/namespace-select-filter.scss

@@ -59,6 +59,8 @@
     &__option {
       white-space: normal;
       word-break: break-all;
+      padding: 4px 8px;
+      border-radius: 3px;
     }
   }