Added extendRequestParams to downloadItem()

[drola]

No description provided.

[psolom]

Thanks for the contribution!
Have you tested this? How it works for you?

[drola]

Let's start with the bug that I was trying to fix.
I pass a token between all requests to the backend to do authorization. Our users found out that everything works except downloading the files.When looking through the code I discovered that downloadItem() doesn't call fm.settings.callbacks.beforeSetRequestParams. Comparing that to other actions I figured out that calling extendRequestParams() is the most appropriate solution for downloadItem().

I tested this and the tokens are now passed to the download request as they should be.

[psolom]

I see now, thanks for the details. Merged.