zeta: Send up diagnostics with prediction requests (#24384)

This PR makes it so we send up the diagnostic groups as additional data
with the edit prediction request.

We're not yet making use of them, but we are recording them so we can
use them later (e.g., to train the model).

Release Notes:

- N/A

---------

Co-authored-by: Nathan <nathan@zed.dev>

crates/language/src/diagnostic_set.rs

@@ -2,6 +2,7 @@ use crate::{range_to_lsp, Diagnostic};
 use anyhow::Result;
 use collections::HashMap;
 use lsp::LanguageServerId;
+use serde::Serialize;
 use std::{
     cmp::{Ordering, Reverse},
     iter,
@@ -25,7 +26,7 @@ pub struct DiagnosticSet {
 /// the diagnostics are stored internally as [`Anchor`]s, but can be
 /// resolved to different coordinates types like [`usize`] byte offsets or
 /// [`Point`](gpui::Point)s.
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq, Serialize)]
 pub struct DiagnosticEntry<T> {
     /// The range of the buffer where the diagnostic applies.
     pub range: Range<T>,
@@ -35,7 +36,7 @@ pub struct DiagnosticEntry<T> {
 
 /// A group of related diagnostics, ordered by their start position
 /// in the buffer.
-#[derive(Debug)]
+#[derive(Debug, Serialize)]
 pub struct DiagnosticGroup<T> {
     /// The diagnostics.
     pub entries: Vec<DiagnosticEntry<T>>,
@@ -43,6 +44,20 @@ pub struct DiagnosticGroup<T> {
     pub primary_ix: usize,
 }
 
+impl DiagnosticGroup<Anchor> {
+    /// Converts the entries in this [`DiagnosticGroup`] to a different buffer coordinate type.
+    pub fn resolve<O: FromAnchor>(&self, buffer: &text::BufferSnapshot) -> DiagnosticGroup<O> {
+        DiagnosticGroup {
+            entries: self
+                .entries
+                .iter()
+                .map(|entry| entry.resolve(buffer))
+                .collect(),
+            primary_ix: self.primary_ix,
+        }
+    }
+}
+
 #[derive(Clone, Debug)]
 pub struct Summary {
     start: Anchor,