materialize-bigquery: validate bignumeric columns as integer or number

We used to create number columns as "bignumeric" (see
estuary#859.), and now create strings formatted as integer
columns as "bignumeric". Allowing "bignumeric" columns to be either integer or number compatible
allows both new and old materializations to work.

materialize-bigquery/sqlgen.go

@@ -87,7 +87,7 @@ var bqDialect = func() sql.Dialect {
 		sql.ColValidation{Types: []string{"int64"}, Validate: sql.IntegerCompatible},
 		sql.ColValidation{Types: []string{"float64"}, Validate: sql.NumberCompatible},
 		sql.ColValidation{Types: []string{"json"}, Validate: sql.MultipleCompatible},
-		sql.ColValidation{Types: []string{"bignumeric"}, Validate: sql.IntegerCompatible},
+		sql.ColValidation{Types: []string{"bignumeric"}, Validate: bignumericCompatible},
 		sql.ColValidation{Types: []string{"date"}, Validate: sql.DateCompatible},
 		sql.ColValidation{Types: []string{"timestamp"}, Validate: sql.DateTimeCompatible},
 	)
@@ -118,6 +118,13 @@ var bqDialect = func() sql.Dialect {
 	}
 }()
 
+// bignumericCompatible allows either integers or numbers, since we used to create number columns as
+// "bignumeric" (now they are float64), and currently create strings formatted as integers as
+// "bignumeric". This is needed for compatibility for older materializations.
+func bignumericCompatible(p pf.Projection) bool {
+	return sql.IntegerCompatible(p) || sql.NumberCompatible(p)
+}
+
 // stringCompatible allow strings of any format, arrays, or objects to be materialized.
 func stringCompatible(p pf.Projection) bool {
 	if sql.StringCompatible(p) {