Support JOIN table alias

[houqp]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

Support self join queries with table alias:

SELECT * FROM t1 JOIN t1 as t2 ON t1.id = t2.id

Describe the solution you'd like

Datafusion should execute this query without error.

[Dandandan]

This might also resolve TPC-H queries 7 / 8 which fail with:
Error: Plan("Schema contains duplicate unqualified field name \'n_nationkey\'")