Generate risk incidences when Siegfried outputs warnings on format identification

[SugaryLump]

• A new risk pertaining to Siegfried file format detector warnings was added
• SiegfriedPlugin now generates risk incidences of the aforementioned risk when a warning is output on file format detection
  • If previous incidences of this risk exist on the source files when this plugin is run, then they are automatically set as "Mitigated" by the plugin (new "Unmitigated" incidences may still be created during this execution)
• SiegfriedPlugin now writes a note to all the PREMIS Format Notes for source files that includes any output Siegfried warning
• EditFileFormatPlugin has a new boolean parameter that will clear the source files' risk incidences/PREMIS notes relating Siefried warnings
  • If this parameter is left as false (default), PREMIS notes will be preserved and no risk incidences will be modified