[FEATURE REQUEST] "Export" and "Import" features

[the-liquid-metal]

Add a "Export" and "Import" buttons in "Files/folders" section

Export feature: in the form of dialog window:

1. Filename and location field.
2. Format field. Available options:
   • json. everything that szyszka need to build identical list in Files/Folders table.
   • Windows bat/PS.
   • unix shell.
   • txt.
   • csv.

Import feature: in the form of dialog window:

1. Filename and location field.
2. Insert position field. Available position:
   • at the begining.
   • at the end.
3. Edited status field. available status:
   • manual edited
   • auto generated

Import feature only accept the same format as export feature.

Edited status only applied if imported file is not json.

If the imported file contains invalid entries, there should be a prompt whether the process will be continued or be cancelled. If invalid entries succeed inserted into Files/Folders table, these rows must be stated as error.

similar issues: #87, #61