We try to distinguish truly block-cloned (i.e. "reflinked") files from
files that we failed to clone and instead had to use `io.Copy()` on,
because this might be useful to the operator/administrator to gauge the
space savings or gain awareness of filesystem configuration problems.
* ui: restore --delete indicates number of deleted files
* adds new field `FilesDeleted` to the State struct, JSON and text progress updaters
* increment FilesDeleted count when ReportedDeletedFile
* ui: collect the files to be deleted, delete, then update the count post deletion
* docs: update scripting output fields for restore command
ui: report deleted directories and refactor function name to ReportDeletion
