First cut of the module

[babolivier]

This work is happening in the context of the Tchap mainlining. In Tchap, when a user is registered (which always requires an email to be set), the email is automatically bound to a Sydent instance using the internal API (so that their email can be looked up immediately, and without having to go through additional manual validation).

This module implements this behaviour by using the on_user_registration account validity callback, as well as a module API method added in matrix-org/synapse#12195.

The CI is expecting to fail since matrix-org/synapse#12195 hasn't made it into mainline CI yet, but it's all passing locally.

[reivilibre]

Looks good to me, I assume you've tested it works, so the comment is really just a question about how it works (with perhaps a point that it might be nice to document it readily, as it seems not immediately obvious).

[babolivier]

I've rewritten a bit of the module so it now uses the callback to matrix-org/synapse#12302, and binds assocs when they're verified on the HS rather than only on registration.
CI is still failing (because none of the PRs have made it into a stable release of Synapse), but I've ran the CI against a local branch that has both PRs merged in and it's passing fine:

$ ./scripts-dev/lint.sh 
+ isort synapse_bind_sydent tests
+ python3 -m black synapse_bind_sydent tests
All done! ✨ 🍰 ✨
3 files left unchanged.
+ flake8 synapse_bind_sydent tests
+ mypy synapse_bind_sydent tests
Success: no issues found in 3 source files

Code has changed quite a bit since the review

[reivilibre]

Looks fine otherwise, I think!

[reivilibre]

Seems to require reformatting, but AST-wise this is fine

Edit: actually it looks like black might be broken? Hrmph.