Support struct_expr generate struct in sql

[Ted-Jiang]

Which issue does this PR close?

Related #2043.

Rationale for this change

Support construct a struct in SQL.

select STRUCT(1,2,3);
+------------------------------------+
| struct(Int64(1),Int64(2),Int64(3)) |
+------------------------------------+
| {"f_0": 1, "f_1": 2, "f_2": 3}     |
+------------------------------------+
1 row in set. Query took 0.003 seconds.

What changes are included in this PR?

Are there any user-facing changes?

Now the struct Field only support default name like f_n
I want to use `select struct(1 as a)' as field name, but got error in parsing

 select STRUCT(1 as a);  🤔 Invalid statement: sql parser error: Expected ), found: as

I think it should fix in sql-parse, if wrong plz correct me.
I will create follow up ticket for this, if this PR is fine.

[andygrove]

This looks like it is generating a struct where all of the fields have the same name. I would expect that to cause an error.

[Ted-Jiang]

Fix, It should only need the DataType info, no need for fields name

[andygrove]

format!("f_{}", i) is duplicated in each match. Could we create the column name once before the match statement?

[Ted-Jiang]

Sure! Thanks for your advice.

[andygrove]

We should return an Err rather than panic here

[andygrove]

LGTM once the error handling is updated to return Err rather than panic. Thanks @Ted-Jiang

[andygrove]

Thanks @Ted-Jiang