Add support for downloading TSV/MD from query tab

[LalitMaganti]

We have copy to clipboard but for very large row counts, it's too slow. Add download capability for working around it.

[stevegolton]

We already have this?

[LalitMaganti]

I think it's for the query mode on the ominbox.

[stevegolton]

Ah, OK I'll update the issue title

[LalitMaganti]

Ah my mistake sorry I did mean tab not page.