MSC2836 threading: part 2 (#1596)

* Update GMSL

* Add MSC2836EventRelationships to fedsender

* Call MSC2836EventRelationships in reqCtx

* auth remote servers

* Extract room ID and servers from previous events; refactor a bit

* initial cut of federated threading

* Use the right client/fed struct in the response

* Add QueryAuthChain for use with MSC2836

* Add auth chain to federated response

* Fix pointers

* under CI: more logging and enable mscs, nil fix

* Handle direction: up

* Actually send message events to the roomserver..

* Add children and children_hash to unsigned, with tests

* Add logic for exploring threads and tracking children; missing storage functions

* Implement storage functions for children

* Add fetchUnknownEvent

* Do federated hits for include_children if we have unexplored children

* Use /ev_rel rather than /event as the former includes child metadata

* Remove cross-room threading impl

* Enable MSC2836 in the p2p demo

* Namespace mscs db

* Enable msc2836 for ygg

Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>

setup/mscs/mscs.go

@@ -16,15 +16,18 @@
 package mscs
 
 import (
+	"context"
 	"fmt"
 
 	"github.com/matrix-org/dendrite/setup"
 	"github.com/matrix-org/dendrite/setup/mscs/msc2836"
+	"github.com/matrix-org/util"
 )
 
 // Enable MSCs - returns an error on unknown MSCs
 func Enable(base *setup.BaseDendrite, monolith *setup.Monolith) error {
 	for _, msc := range base.Cfg.MSCs.MSCs {
+		util.GetLogger(context.Background()).WithField("msc", msc).Info("Enabling MSC")
 		if err := EnableMSC(base, monolith, msc); err != nil {
 			return err
 		}