storage: adds new interface `Transactional` which is to be implemented by storage providers that can support transactions.
storage: adds new interface `Transactional` which is to be implemented by storage providers that can support transactions.

Signed-off-by: Amir Aslaminejad <de2d55548147c7442d793bd98b29a138007f9844@gmail.com>

ory/fosite,ory-am/fosite,ory-am/fosite,ory/fosite