Fullscreen MediaViewer refactor

- Moved media related logic into notedeck instead of the ui crate,
  since they pertain to Images/ImageCache based systems

- Made RenderableMedia owned to make it less of a nightmware
  to work with and the perf should be negligible

- Added a ImageMetadata cache to Images. This is referenced
  whenever we encounter an image so we don't have to
  redo the work all of the time

- Relpaced our ad-hoc, hand(vibe?)-coded panning and zoom logic
  with the Scene widget, which is explicitly designed for
  this use case

- Extracted and detangle fullscreen media rendering from inside of note
  rendering.  We instead let the application decide what action they
  want to perform when note media is clicked on.

- We add an on_view_media action to MediaAction for the application to
  handle. The Columns app uses this toggle a FullscreenMedia app
  option bits whenever we get a MediaAction::ViewMedis(urls).

Signed-off-by: William Casarin <jb55@jb55.com>

Cargo.lock

@@ -3423,10 +3423,12 @@ dependencies = [
  "base32",
  "bech32",
  "bincode",
+ "blurhash",
  "dirs",
  "eframe",
  "egui",
  "egui-winit",
+ "egui_extras",
  "ehttp",
  "enostr",
  "fluent",
@@ -3576,7 +3578,6 @@ name = "notedeck_ui"
 version = "0.5.8"
 dependencies = [
  "bitflags 2.9.1",
- "blurhash",
  "eframe",
  "egui",
  "egui-winit",