Add support to mark videos as spoilers (#2255)

* Add support for MSC4193: Spoilers on Media

* Clarify variable names and wording

* Restore list atom

* Improve spoilered image UX with autoload off

* Use `aria-pressed` to indicate attachment spoiler state

* Improve spoiler button tooltip wording, keep reveal button from conflicting with load errors

* Make it possible to mark videos as spoilers

* Allow videos to be marked as spoilers when uploaded

* Apply requested changes

* Show a loading spinner on spoiled media when unblurred

---------

Co-authored-by: Ajay Bura <32841439+ajbura@users.noreply.github.com>

src/app/features/room/msgContent.ts

@@ -82,7 +82,7 @@ export const getVideoMsgContent = async (
   item: TUploadItem,
   mxc: string
 ): Promise<IContent> => {
-  const { file, originalFile, encInfo } = item;
+  const { file, originalFile, encInfo, metadata } = item;
 
   const [videoError, videoEl] = await to(loadVideoElement(getVideoFileUrl(originalFile)));
   if (videoError) console.warn(videoError);
@@ -91,6 +91,7 @@ export const getVideoMsgContent = async (
     msgtype: MsgType.Video,
     filename: file.name,
     body: file.name,
+    [MATRIX_SPOILER_PROPERTY_NAME]: metadata.markedAsSpoiler,
   };
   if (videoEl) {
     const [thumbError, thumbContent] = await to(