Move ora_number_to_ruby_number to Connection base class

The exact same private method was duplicated character-for-character in
both OCIConnection and JDBCConnection. Pull it up into Connection so the
"return BigDecimal instead of Float to avoid rounding errors" rule lives
in one place; subclasses keep calling it as before via inheritance.

Net change: -3 LOC. No behavior change. Full suite is green
(468 examples, 0 failures, 1 pre-existing pending).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: yahonda

lib/plsql/connection.rb

@@ -266,5 +266,12 @@ def drop_session_ruby_temporary_tables
         exec "DROP TABLE #{row[0]}"
       end
     end
+
+    private
+
+      def ora_number_to_ruby_number(num)
+        # return BigDecimal instead of Float to avoid rounding errors
+        num == (num_to_i = num.to_i) ? num_to_i : (num.is_a?(BigDecimal) ? num : BigDecimal(num.to_s))
+      end
   end
 end

lib/plsql/jdbc_connection.rb

@@ -588,10 +588,5 @@ def java_timestamp(value)
       def java_bigdecimal(value)
         value && java.math.BigDecimal.new(value.to_s)
       end
-
-      def ora_number_to_ruby_number(num)
-        # return BigDecimal instead of Float to avoid rounding errors
-        num == (num_to_i = num.to_i) ? num_to_i : (num.is_a?(BigDecimal) ? num : BigDecimal(num.to_s))
-      end
   end
 end

lib/plsql/oci_connection.rb

@@ -301,11 +301,6 @@ def raw_oci_connection
         end
       end
 
-      def ora_number_to_ruby_number(num)
-        # return BigDecimal instead of Float to avoid rounding errors
-        num == (num_to_i = num.to_i) ? num_to_i : (num.is_a?(BigDecimal) ? num : BigDecimal(num.to_s))
-      end
-
       def ora_date_to_ruby_date(val)
         case val
         when DateTime