Support SQL/JSON functions

[felipebz]

The SQL/JSON functions have special syntaxes and they need to be handled like the XML functions:

• [ ] JSON_ARRAY
• [ ] JSON_ARRAYAGG
• [ ] JSON_DATAGUIDE
• [ ] JSON_MERGEPATCH
• [ ] JSON_OBJECT
• [ ] JSON_OBJECTAGG
• [x] JSON_QUERY
• [ ] JSON_SCALAR
• [ ] JSON_SERIALIZE
• [ ] JSON_TABLE
• [ ] JSON_TRANSFORM
• [ ] JSON_VALUE
• [ ] JSON Type Constructor

Also, the parser should accept all JSON conditions:

• [ ] IS JSON
• [ ] JSON_EQUAL
• [ ] JSON_EXISTS
• [ ] JSON_TEXTCONTAINS