add migration process for stuff already bridged

d2m/converters/edit-to-changes.test.js

@@ -38,11 +38,11 @@ test("edit2changes: bot response", async t => {
 					resolve({
 						joined: {
 							"@cadence:cadence.moe": {
-								display_name: "cadence [they]",
+								displayname: "cadence [they]",
 								avatar_url: "whatever"
 							},
 							"@_ooye_botrac4r:cadence.moe": {
-								display_name: "botrac4r",
+								displayname: "botrac4r",
 								avatar_url: "whatever"
 							}
 						}