[ADAP-436] Update bigquery__format_column macro

[jtcohen6]

Update bigquery__format_column macro in accordance with the changes in dbt-labs/dbt-core#7319, to enable a prettier ContractError message.

Rather than just returning <column_name> <data_type> as a string, the macro should return a dictionary containing:

{
    "column_name": "<column_name>",
    "data_type": "<data_type>",
    "formatted": "<column_name> <data_type>"
}

This macro needs to be reimplemented on dbt-bigquery in order to use column.data_type, instead of column.dtype (default implementation). The former handles complex/repeated data types, e.g. ARRAY<STRING>, where the latter reports back only STRING.