Fix Twitter metadata

This partly reverts 1d884fd914
while fixing both the issue it addressed and the issue it caused.

The above commit successfully fixed OpenGraph metadata tags
which until then always showed the user bio instead of post content
by handing the activities AP ID as url to the Metadata builder
_instead_ of passing the internal ID as activity_id.
However, in doing so the commit instead inflicted this very problem
onto Twitter metadata tags which ironically are used by akkoma-fe.

This is because while the OpenGraph builder wants an URL as url,
the Twitter builder needs the internal ID to build the URL to the
embedded player for videos and has no URL property.

Thanks to twpol for tracking down this root cause in #644.

Now, once identified the problem is simple, but this simplicity
invites multiple possible solutions to bikeshed about.

 1. Just pass both properties to the builder and let them pick

 2. Drop the url parameter from the OpenGraph builder and instead
     a) build static-fe URL of the post from the ID (like Twitter)
     b) use the passed-in object’s AP ID as an URL

Approach 2a has the disadvantage of hardcoding the expected URL outside
the router, which will be problematic should it ever change.
Approach 2b is conceptually similar to how the builder works atm.
However, the og:url is supposed to be a _permanent_ ID, by changing it
we might, afaiui, technically violate OpenGraph specs(?). (Though its
real-world consequence may very well be near non-existent.)

This leaves just approach 1, which this commit implements.
Albeit it too is not without nits to pick, as it leaves the metadata
builders with an inconsistent interface.

Additionally, this will resolve the subotpimal Discord previews for
content-less image posts reported in #664.
Discord already prefers OpenGraph metadata, so it’s mostly unaffected.
However, it appears when encountering an explicitly empty OpenGraph
description and a non-empty Twitter description, it replaces just the
empty field with its Twitter counterpart, resulting in the user’s bio
slipping into the preview.
Secondly, regardless of any OpenGraph tags, Discord uses twitter:card to
decide how prominently images should be, but due to the bug the card
type was stuck as "summary", forcing images to always remain small.

Root cause identified by: twpol

Fixes: AkkomaGang/akkoma#644
Fixes: AkkomaGang/akkoma#664

lib/pleroma/web/static_fe/static_fe_controller.ex

@@ -24,7 +24,13 @@ def show(%{assigns: %{notice_id: notice_id}} = conn, _params) do
          true <- Visibility.is_public?(activity.object),
          {_, true} <- {:visible?, Visibility.visible_for_user?(activity, _reading_user = nil)},
          %User{} = user <- User.get_by_ap_id(activity.object.data["actor"]) do
-      meta = Metadata.build_tags(%{url: activity.data["id"], object: activity.object, user: user})
+      meta =
+        Metadata.build_tags(%{
+          activity_id: notice_id,
+          url: activity.data["id"],
+          object: activity.object,
+          user: user
+        })
 
       timeline =
         activity.object.data["context"]