Mute rendering instead of ingress

Previous approach was to keep muted content from getting inserted.

Instead, this version alters it's display.  This makes toggling mutes
on and off externally much more stable (the display changes but we
don't have to rebuild content trees)

For now muted content is collapsed to a red "Muted" tombstone w/ a reason.

crates/notedeck_columns/src/thread.rs

@@ -5,7 +5,7 @@ use crate::{
 };
 
 use nostrdb::{Filter, FilterBuilder, Ndb, Transaction};
-use notedeck::{MuteFun, NoteCache, NoteRef};
+use notedeck::{NoteCache, NoteRef};
 
 #[derive(Default)]
 pub struct Thread {
@@ -74,7 +74,6 @@ impl NotesHolder for Thread {
         _: &[u8; 32],
         _: Vec<Filter>,
         notes: Vec<NoteRef>,
-        _: &MuteFun,
     ) -> Self {
         Thread::new(notes)
     }