The ignore_unavailable option should also ignore indices that are closed

PR for #6471
The 'ignore_unavailable' option should cover both closed and missing indices, but there is a difference between apis. For example search, count and percolate throw cluster block exception when an index is closed, while update setting, mappings etc allow to be executed on a closed index (in fact certain settings can only be changed on a closed index). This difference isn't expressed in IndicesOptions, we can add it, but IMO it shouldn't be exposed as a setting (apis either never ignore closed indices or do ignore/fail closed indices).