Import CSV with pasting

[lana-k]

As a user of sqliteviz,
In order to speed up introp with other local software,
I want to be able to copy and paste into/from sqliteviz.

It's mostly about tiny data volumes and a small convenience of interaction with sqliteviz. For instance you copy something from a spreadsheet (table structure you copy from Libre Office Calc, Google Sheets, etc), instead of moving it to another sheet, saving as CSV and drag'n'dropping to sqliteviz.