feat(12.2-01): add deferred:purge, its daily framework schedule and relation child hooks

- deferred:purge [--days] in lagoon.RuntimeCommands (purge_days, default 5)
- lagoon.FrameworkSchedule entry at purge_at (default 03:00, empty disables)
- conga prepends framework entries as summercms.lagoon[i]:<command>
- pact.Relation{Before,After}{Create,Update,Delete} optional hooks
- lagoon, conga and pact READMEs, scheduling and setup docs

modules/lagoon/migrations_test.go

@@ -45,7 +45,7 @@ func TestRuntimeCommandsRegisterBareAndColonNames(t *testing.T) {
 	for _, c := range cmds {
 		names[c.Name] = true
 	}
-	for _, want := range []string{"migrate", "migrate:rollback", "migrate:status", "key:generate"} {
+	for _, want := range []string{"migrate", "migrate:rollback", "migrate:status", "deferred:purge", "key:generate"} {
 		if !names[want] {
 			t.Fatalf("missing %s", want)
 		}