Support NUMERIC data type via alias to DECIMAL

Example query resulted with an error:

 --> 1:70
  |
1 | create temp table copytest (stringvalue text, intvalue int, numvalue numeric(5,2))
  |                                                                      ^---
  |
  = expected ColumnDefType

Reference: https://www.postgresql.org/docs/current/datatype-numeric.html

NUMERIC is a base type for DECIMAL.