Decouple file transfers from GUI

[spotlesscoder]

One thing I have noticed multiple times already is that when the GUI hangs for some reason (usually low network bandwidth while copying from / to network shares and simultaneously browsing that network share in another files instance), it might hang up totally so I have to kill the files app.

However, that also aborts the running file transfer while that file transfer is not complete. So to reduce the consequences of the files app hanging up, the actual file transfer job should be started in a different process

[jeremypw]

There are many outstanding issues related to file transfers and progress indication. Some work has been done on rewriting file operation code but progress is slow. See for example https://github.com/elementary/files/pull/1154. It is intended that the file operation code be ported to Vala before tackling progress indication and some functions have already been ported.

[spotlesscoder]

OK I see.

However, the issue you linked is rather technical and I don't see through it how it's going to fix this issue