Replicate pending selections separately from other selections

This fixes a panic that would occur when a leader created
a pending selection that overlapped another selection,
because the follower would attempt to treat that pending
selection as non-pending, which would violate the invariant
that selections are sorted and disjoint.

crates/rpc/proto/zed.proto

@@ -853,9 +853,10 @@ message UpdateView {
         repeated ExcerptInsertion inserted_excerpts = 1;
         repeated uint64 deleted_excerpts = 2;
         repeated Selection selections = 3;
-        EditorAnchor scroll_top_anchor = 4;
-        float scroll_x = 5;
-        float scroll_y = 6;
+        optional Selection pending_selection = 4;
+        EditorAnchor scroll_top_anchor = 5;
+        float scroll_x = 6;
+        float scroll_y = 7;
     }
 }
 
@@ -872,9 +873,10 @@ message View {
         optional string title = 2;
         repeated Excerpt excerpts = 3;
         repeated Selection selections = 4;
-        EditorAnchor scroll_top_anchor = 5;
-        float scroll_x = 6;
-        float scroll_y = 7;
+        optional Selection pending_selection = 5;
+        EditorAnchor scroll_top_anchor = 6;
+        float scroll_x = 7;
+        float scroll_y = 8;
     }
 }
 

crates/rpc/src/rpc.rs

@@ -6,4 +6,4 @@ pub use conn::Connection;
 pub use peer::*;
 mod macros;
 
-pub const PROTOCOL_VERSION: u32 = 43;
+pub const PROTOCOL_VERSION: u32 = 44;