[FEATURE]: Import of .hcmask files

[StrongbirdXL]

Description

It would be handy to have the ability to import .hcmask files in hashtopolis. currently i have to enter them in the Import supertask location. However i also have .hcmask files which are quite big, at this moment i cannot copy and paste them there and have it work. i noticed if you go over a certain amount of lines hashtopolis would not accept it and would not create the task. even though no error showed up. Perhaps for this scenario it would also be handy to have a upload function for the .hcmask to be able to be processed.