For now, we disable the new `com.devture.shared_secret_auth` login type
by default, because it causes problems with Element:
https://github.com/vector-im/element-web/issues/19605

This also becomes the first module to use the new Synapse module system
that got introduced in Synapse v1.46.0.

Despite these upgrades, things should remain functionally identical
as far as bridges, matrix-corporal or other consumers are concerned.