[REPL] Bug related to hitting enter from middle of line containing semi-colon

[alancai98]

Copied from this PR comment: #9 (comment).

There's a bug in the REPL where hitting enter from the middle of the query containing a semi-colon will repeat the query. For example, if a user typed the following query and moved the cursor to the left (this could be common when adjusting the query), the query would be repeated in the output.

PartiQL> SELECT COUNT(1) FROM <<{'a': 1}, {'a': 2}>>;
==='
<<
  {
    _1: 2
  }
>>
PartiQL> SELECT COUNT(1) FROM <<{'a': 1}, {'a': 2}>>;

---
OK!
PartiQL>