Add support for using aliases created in select list in GROUP BY and ORDER BY

[alancai98]

Thanks @alancai98, I can use Order By now. I also want to add alias support for Order By and Group By. Currently, following queries are not working because of missing bindings.

• SELECT a as b FROM table ORDER BY b
• SELECT a as b FROM table GROUP BY b

Do you mind if I open a new PR to support for aliases, if can implement? or Do I need to open an issue for this?

Originally posted by @onurkuruu in #554 (comment)

[johnedquinn]

Taking a look at this. Currently, the following query results in: EvaluationException

SELECT a AS b FROM << {'a': 5}, {'a': 6} >> ORDER BY b;

And, the following query works (Note the ORDER BY <variable>):

SELECT a AS b FROM << {'a': 5}, {'a': 6} >> ORDER BY a;

[
  {
    'b': 5
  },
  {
    'b': 6
  }
]

The goal should be to get the first query to work.

[johnedquinn]

So, taking a look @ this again. I haven't done a ton of research, but I saw this tid-bit on StackOverflow making me think that GROUP BY will never support projection aliases.

Anyways, I made some changes to ORDER BY, and I'll be posting a PR soon.