ephemeral events: add support for MSC2409 ephemeral events

Closes #19

config/appservice.go

@@ -17,6 +17,8 @@ type appservice struct {
 
 	Database database `yaml:"database"`
 
+	EphemeralEvents bool `yaml:"ephemeral_events"`
+
 	ASToken string `yaml:"as_token"`
 	HSToken string `yaml:"hs_token"`
 }

config/registration.go

@@ -10,6 +10,7 @@ import (
 func (cfg *Config) CopyToRegistration(registration *as.Registration) error {
 	registration.ID = cfg.Appservice.ID
 	registration.URL = cfg.Appservice.Address
+	registration.EphemeralEvents = cfg.Appservice.EphemeralEvents
 
 	falseVal := false
 	registration.RateLimited = &falseVal