Sending URL Preview Bundles (MSC 4095) (#34150)

* Fetches link previews for all links in message (instead of just the first one)

* message url component to display preview for multiple urls

* Revert visible behaviour back to only showing one URL preview

While fetching all link previews in the text message.

* Moved URL preview VM to MessageComposer

* Added com.beeper.linkpreviews to messages sent with the markdown compositor

* MSC 4452 implemented for the older (markdown) composer

* claude told me to use logger instead of console

* Previews generated with snapshot instead of vm

* moved attachPreviews to a separate file

* added attach URL previews to rich text editor

* don't let attachUrlPreviews block clearning the composer

* fixed linter errors

* moved url preview behind labs feature gate

* passed linters

* moved lab feature checking to where attach preview is used

* claude wrote some unit tests for url previewing

* fixed linter errors

* added feature to labs.md

* fixed linter errors

* fixed oxfmt error

* set previews to none if all previews failed

* resolved PR reviews besides the ones that requires a larger code change

* moved url preview VM creation to message composer

* removed delay when clearing composer url preview on message send

* minor changes to stop using globals everywhere

* moved debouncing responsibility to urlpreviewVM

* minor lint fixes

* added comment

* remove composer content from the state of urlpreview, moved it to the vm

* urlpreviewwrapper depends on the vm only

* added comments

* edited the comment

* updated snapshots

* claude fixed tests

* enable feature for tests that requires MSC4095

* updated snapshot

docs/labs.md

@@ -130,3 +130,7 @@ Enables logging in to Element Web/Desktop by using Element X to scan a QR code.
 Requires server support, based on the v2024 edition of [MSC4108](https://github.com/matrix-org/matrix-spec-proposals/pull/4108).
 Can only be configured via config.json, as labs flags cannot be set until after login, and are cleared on log out. The UI option is disabled.
 Note, this does not affect the existing `Link new device` flow using the same MSC.
+
+## URL Preview Bundle (MSC4095) (`feature_msc4095_url_preview_bundle`)
+
+Attaches URL preview information generated by the homeserver on messages sent.