In Duplicati.CommandLine.RecoveryTool, the `index` and `list` commands
do not recognize Duplicati backup files when those files are in paths
containing dashes.
For example, without this change, if you call
```
Duplicati.CommandLine.RecoveryTool index C:\Temp\duplicati-tests\recovery-tool\backup-files
```
the Duplicati backup files are displayed, but the recovery tool
reports "Not a Duplicati file, ignoring" for each of them.