Resume multiple payjoins

[DanGould]

Fix #267

Send and receive now open sessions with the directory that can be persisted. This includes an e2e test in the UI. As of this PR each session is persisted forever, but a follow up will handle session expiration and archive past sessions for both sender and receiver

This also introduces a new payjoin-cli resume command that continues all active send and receive sessions from the database.

struct SessionContext

The V2Context has been replaced SessionContext that contains an address for the session's URI and an expiry time at which the session is no longer usable.

• [x] Save multiple payjoin send/receive sessions automatically upon send/receive command
• [x] Resume all open send/receive sessions with new resume command
• [x] send command checks bip21 pj=url against the database, resumes if it exists.
• [x] receive command lists and resumes active sessions and their bip21s
• [x] ensure e2e test runs in CI

Closes #205 as a side effect

[DanGould]

@grizznaut This is not yet quite buttoned up for release but is ready for a review. Before it gets released I'd like the end-to-end test to run the directory and ohttp relay locally. However I think I will leave session expiration to a follow up PR to be completed by the end of next week for the sake of review simplicity.

[DanGould]

I just rebased on master so that tests could run once more