Render captions to m.file, m.image, m.video, and m.audio (#2059)

* Add rendering image captions

* Handle sending captions for images

* Fix caption rendering on m.video and m.audio too

* Remove unused renderBody() parameter

* Fix m.file rendering body instead of filename where possible

* Add caption rendering for generic files

+ Fix video and audio not properly sending captions

* Use m.text for captions & render on demand

* Allow custom HTML in sending captions

* Don't *send* captions

* mvoe content const into renderCaption()

---------

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

src/types/matrix/common.ts

@@ -43,6 +43,7 @@ export type IThumbnailContent = {
 export type IImageContent = {
   msgtype: MsgType.Image;
   body?: string;
+  filename?: string;
   url?: string;
   info?: IImageInfo & IThumbnailContent;
   file?: IEncryptedFile;
@@ -51,6 +52,7 @@ export type IImageContent = {
 export type IVideoContent = {
   msgtype: MsgType.Video;
   body?: string;
+  filename?: string;
   url?: string;
   info?: IVideoInfo & IThumbnailContent;
   file?: IEncryptedFile;
@@ -59,6 +61,7 @@ export type IVideoContent = {
 export type IAudioContent = {
   msgtype: MsgType.Audio;
   body?: string;
+  filename?: string;
   url?: string;
   info?: IAudioInfo;
   file?: IEncryptedFile;
@@ -67,6 +70,7 @@ export type IAudioContent = {
 export type IFileContent = {
   msgtype: MsgType.File;
   body?: string;
+  filename?: string;
   url?: string;
   info?: IFileInfo & IThumbnailContent;
   file?: IEncryptedFile;