Boilerplate for web and desktop to look for keyserverID during notifications session creation and notification decryption

Summary:
This differential updates web and desktop code so that:

1. The keyserverID is an argument to methods that create session.
2. The keyserverID is an argument of methods that decrypt notifications on desktop.

Actually using this argument will be introduced in next diff.

Test Plan:

1. Flow
2. Test that notifs aren't broken on web and desktop

Reviewers: michal

Reviewed By: michal

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D11303