[FEATURE] Add multi-hash and multi-text import support

[Theadri1900]

Is your feature request related to a problem? Please describe.
You can't import multiple hash or multiple text on the app like you can import multiple file. So, if you have like 50 texts to sign, it is very long to copy paste one by one.

Describe the solution you'd like
Let the possibility for user to import multiple-hash with a special file like CSV :
"hash", "DocType", "source", "extra:data"

For text, let possibility to import .txt file.

Plus, find a solution to apply multiple same properties to multiple file like make all files "DocumentType=Diploma".