support for multiline queries in REPL

[MaxDesiatov]

Hi, many thanks for this useful utility.

It would be great if REPL supported running multiline queries.

With the suggested logic it would not start issuing the query to Athena until a semicolon is present in the input.

This would also align athenai with other SQL REPLs out there, specifically psql.

Right now if a multiline query is pasted into REPL only the first line is executed, which causes query syntax errors.