Is your feature request related to a problem?

It is not related to the particular problem but the design.

Describe the solution you'd like to see

Dex has an interface for a storage. To be able to cancel long-running storage operations, we can pass context to all methods of this interface.

Describe alternatives you've considered

Leave things as they are or add any sane timeout.

Additional context

etcd storage already uses context for its operations.