bc2pg postgres table creation - add precision to numeric types

[smnorris]

Data types for numbers in Oracle are generally described by the catalogue api in format 'data_type': 'NUMBER', 'data_precision': '4'.

The precision is not currently used when creating output table in postgres, bc2pg writes all NUMBER columns to a generic NUMERIC type as defined by sqlalchemy, with no precision (despite what comment says, perhaps this is something that was removed)
https://github.com/smnorris/bcdata/blob/main/bcdata/database.py#L156

This is not an issue when working with the data in postgres, but on dumping to other formats the type guessing can be problematic - it would probably be better if the postgres type is better defined.

[smnorris]

Yes, this was tweaked with #117
67bde22

A better NUMBER -> NUMERIC lookup is needed.
https://aws.amazon.com/blogs/database/convert-the-number-data-type-from-oracle-to-postgresql-part-1/