implement JSON type in FE

[murphyatwork]

What type of PR is this：

• bug
• feature: add json type in FE
• enhancement
• others

Modification

• add keyword json for type
• add json type in Type.java
• add json type in thrift
• support type casting for json
• implement -> syntax for json_query function
• JSON is not allowed used for partition by, distributed by, order by, group by ...

Not included

• Infra: JSON type infra #3089
• BE implementation: implement JSON type in BE #3085
• Json function:

[imay]

Is this arrow_expr neceesary for JOSN?
I'm a little worried if this definition will be conflict with lambda expression?

[murphyatwork]

The arrow expression looks like '->', currently used a syntax sugar for JSON.

Current implementation of arrow expression is just translate into json_query($value, $path), which would conflict with some other usage like lambda expression.

However, I think it's quite easy to avoid conflicts, just look up the context of this expression, and translate it according to the context.

Anyway, some existing jsonpath sugar, like col->'field', col.k1.k2, col[k1][k2], are always has ambiguity with other SQL syntax, there's no simple approach to create an unique syntax.

[imay]

What I'm worried is that these two expr will cause shift/reduce conflict when parsing phase if we support lambda later.
One way is to create a super expr compatible with both ArorwExpr and Lambda.
Is it possible?

[murphyatwork]

One possible way:

arrow_expr is defined as : left_expr '->' right_expr.

Resolve rule:

1. If left_expr could be resolved a json type, including column_ref or function result, it's a json access expression. And the right_expr must be a literal string expression.
2. Otherwise, left_expr could not be resolved, the whole expression is recognized as lambda expression

Which means, in parsing phase they could not be differentiated, only analyzer could tell the truth.