Rewrite export tool to use existing components to render output, use existing source URLs for media

src/components/structures/MessagePanel.js

@@ -41,7 +41,7 @@ const continuedTypes = ['m.sticker', 'm.room.message'];
 
 // check if there is a previous event and it has the same sender as this event
 // and the types are the same/is in continuedTypes and the time between them is <= CONTINUATION_MAX_INTERVAL
-function shouldFormContinuation(prevEvent, mxEvent) {
+export function shouldFormContinuation(prevEvent, mxEvent) {
     // sanity check inputs
     if (!prevEvent || !prevEvent.sender || !mxEvent.sender) return false;
     // check if within the max continuation period