feat: support subquery in FROM clause

[MingjiHan99]

This PR introduces alias and output_alias to the binder context.

For table:

create table t(a int, b int);

and query:

select x.a, y.a from 
    (select -a as a from t) as x,
    (select -b as a from t) as y;

After binding from t, the context will be:

[alias]
a = { t: "$t.a" }
b = { t: "$t.b" }
[output_alias]

Later when binding a, it will lookup the alias map and get node $t.a.

After binding select -a as a from t, the context will be:

[alias]
a = { t: "(- $t.a)" }
b = { t: "$t.b" }
[output_alias]
a = "(ref (- $t.a))"

The node ref is used to refer an expression as a whole and prevent optimization.

Then the output_alias will be moved to the upper context:

[alias]
a = { x: "(ref (- $t.a))" }
[output_alias]

Later the binder will get (ref (- $t.a)) when binding select x.a.

The final binding result of this query will be:

(proj (list (ref (- $t.a)) (ref (- $t.b)))
  (join inner true
    (proj (list (- $t.a))
      (scan $t (list $t.a $t.b)))
    (proj (list (- $t.b))
      (scan $t (list $t.a $t.b)))
))

Next it comes to the optimizer. The projection pushdown rules are fixed to properly treat (- $t.a) instead of $t.a as a basic unit above the join node.