* 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
This keeps backwards compatibility with the previous empty structs.
And maybe we'd want to put other fields into the inner struct later,
rather than the outer message.
To clear the status lines, they should be set to an empty array to
prevent future updates of those lines. Setting the status lines to an
array containing an empty string is wrong as this causes the output to
continuously add that empty status line after each message.
