feat(test): add sqllogictest

[skyzh]

This PR adds sqllogictest parser. The runner is not complete yet, but now we can start writing test cases using the sqllogictest grammar.

part of https://github.com/cmu-db/bustub/issues/343

[skyzh]

The query grammar:

query rowsort
select v2, v2 + 1, sum(v1) from t group by v2 + 1, v2
----
1 2 3
3 4 5
2 3 7

can be parsed, but not supported in the runner yet.

[skyzh]

Usage:

./bin/bustub-sqllogictest ../test/sql/intro.slt