threads: add initial thread support

This is a really dumb and broken version of threads, but it will be our
foundation for future changes.

All it currently does is load whatever notes we have locally for a
thread in chronological order. It currently does not open any
subscriptions. It is not clear what is replying to what, but hey, its a
start.

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

src/ui/mod.rs

@@ -10,6 +10,7 @@ pub mod preview;
 pub mod profile;
 pub mod relay;
 pub mod side_panel;
+pub mod thread;
 pub mod username;
 
 pub use account_management::AccountManagementView;
@@ -22,6 +23,7 @@ pub use preview::{Preview, PreviewApp, PreviewConfig};
 pub use profile::{profile_preview_controller, ProfilePic, ProfilePreview};
 pub use relay::RelayView;
 pub use side_panel::{DesktopSidePanel, SidePanelAction};
+pub use thread::ThreadView;
 pub use username::Username;
 
 use egui::Margin;