vschema ddl: add grammar to accept qualified tables (vitessio#12577) (vitessio#12747)

Signed-off-by: Hormoz Kheradmand <hormoz.kheradmand@shopify.com>
Signed-off-by: Florent Poinsard <florent.poinsard@outlook.fr>
Co-authored-by: Hormoz Kheradmand <hkdsun@users.noreply.github.com>

Author: frouioui