feat: add DECIMAL and BIGDECIMAL as aliases for NUMERIC and BIGNUMERIC to scalar types enums

[tswast]

#626 (comment)

[tswast]

On second-thought, these are actually called NUMERIC and BIGNUMERIC in BigQuery. I don't know if we want to be adding aliases outside of those we already have for Legacy SQL support.

🤔

[jimfulton]

But these are defined as valid standard sql aliases here: https://cloud.google.com/bigquery/docs/reference/standard-sql/data-types#decimal_types

[jimfulton]

IMO, this is a bug not a feature. :)

[jimfulton]

@tswast shall I address this?

[tswast]

Gotcha. I didn't realize the backend had these as aliases. Yes, let's go for it.

[jimfulton]

I can't find any use of SqlParameterScalarTypes.

I searched:

• the google and test source directories.
• the internet using google. :)

Is there a reason we think we need this (other than for our internal use)?

[tswast]

I'd like to use those in code samples where folks have STRUCT type query parameters with sub-fields

Honestly, it'd be much more useful if we supplemented the class to allow a builder-style construction where we add a with_name(...) function that makes a copy of the parameter type but adds a name.

[tswast]

Closed by #638