Enhancement: Backup options --files-from-verbatim and --files-from-raw

The new backup options `--files-from-verbatim` and `--files-from-raw`
read a list of files to back up from a file. Unlike the existing `--files-from`,
these options do not interpret the listed filenames as glob patterns;
whitespace in filenames is preserved as-is and no pattern expansion is done.

These new options are recommended over `--files-from` when generating the
list of files to back up from a script. Please see the documentation for specifics.

https://github.com/restic/restic/issues/2944
https://github.com/restic/restic/issues/3013