Include eventid in log lines when processing incoming federation transactions (#3959)

when processing incoming transactions, it can be hard to see what's going on,
because we process a bunch of stuff in parallel, and because we may end up
recursively working our way through a chain of three or four events.

This commit creates a way to use logcontexts to add the relevant event ids to
the log lines.

0 files changed, 0 insertions, 0 deletions