- Replace ECPublicKey with CurvePublicKey

This is a very lightweight object, no need for caching

LoggerAdapter is not subsciptable in python 3.10

Its expected that these structs come from a xmpp library. This allows
type checking to work without the xmpp library having a dependency on
omemo-dr.

- Allow applications to pass a context string

Make get_identity_infos() into a more flexible method