[MySQL] Migrated tables CREATE TABLE syntax not idempotent

[ssherwood]

Running voyager to migrate a set of tables from MySQL (MariaDB 10.5) and identified a possible improvement.

Example:

DROP TABLE IF EXISTS `foo_table`;
CREATE TABLE `foo_table` (
  `FOO_ID` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
  `BAZ_NM` varchar(250) DEFAULT NULL,
  PRIMARY KEY (`FOO_ID`)
);

In the resulting output from Voyager, the table create looks like this:

CREATE TABLE foo_table (
    foo_id bigserial,
    bar_nm varchar(250),
    PRIMARY KEY (foo_id)
) ;
ALTER SEQUENCE foo_table_foo_id_seq RESTART WITH 1;

The original DROP TABLE IF EXISTS is ignored (which I think is a good thing) but I also think it is more appropriate for a Yugabyte DDL to attempt to produce properly idempotent statements as much as possible. At least a configuration option should be able to use CREATE TABLE IF NOT EXISTS syntax instead.