Add support for individual/global facet stickyness

- You can set all facets sticky / not sticky through AfsFacetManager or
  AfsSearch.
- You can declare facet by facet which is sticky and which is not
  sticky.

Remember that, as of AFS v7.6 and v7.7, facets declared sticky on
indexation side remain sticky even if you set all facets non sticky or
set it explicitly sticky on request side.