Merge changes Ie5999dda,I2853cd3c,I7d9f1fe3,I19576654,I158af793, ...

* changes:
  [res] Don't stat asset providers on RO filesystems
  [res] Change OverlayableInfo to hold string views
  [res] Change staged alias container to vector
  [res] Change callback from function to function_ref
  [res] Reuse memory in RebuildFilterList()
  [res] Split keys and values in Theme::Entry vector
  [res] Properly create ZipAssetsProvider with fd