fix(bigquery)!: Canonicalize struct & array inline constructor

[VaggelisD]

Public slack context

BigQuery allows Array/Struct inline construction such as:

SELECT 
   STRUCT<a INT, b STRING>(1, 'foo'),
   ARRAY<INT>[1, 2, 3], 
   ...

Up until now this was parsed as a single exp.DataType node with the inlined values stored in it's values arg. However, this is (1) semantically incorrect as exp.DataType should only encode type information and (2) it doesn't facilitate transpilation in any way.

This PR aims to decouple the actual values from exp.DataType and enable seamless transpilation (mainly focused towards DDB) by canonicalizing such expressions to CAST(<values> AS <type>).

This is done by transforming the parsed exp.DataType into an exp.Cast, with the values now stored in an exp.Array / exp.Struct as the cast's LHS and the type as the RHS.