Show inline previews for LSP document colors (#32816)

https://github.com/user-attachments/assets/ad0fa304-e4fb-4598-877d-c02141f35d6f

Closes https://github.com/zed-industries/zed/issues/4678

Also adds the code to support `textDocument/colorPresentation`
counterpart that serves as a resolve mechanism for the document colors.
The resolve itself is not run though, and the editor does not
accommodate color presentations in the editor yet — until a well
described use case is provided.

Use `lsp_document_colors` editor settings to alter the presentation and
turn the feature off.

Release Notes:

- Start showing inline previews for LSP document colors

crates/diagnostics/src/diagnostics_tests.rs

@@ -1,7 +1,7 @@
 use super::*;
 use collections::{HashMap, HashSet};
 use editor::{
-    DisplayPoint, EditorSettings, InlayId,
+    DisplayPoint, EditorSettings,
     actions::{GoToDiagnostic, GoToPreviousDiagnostic, Hover, MoveToBeginning},
     display_map::{DisplayRow, Inlay},
     test::{
@@ -870,11 +870,11 @@ async fn test_random_diagnostics_with_inlays(cx: &mut TestAppContext, mut rng: S
 
                         editor.splice_inlays(
                             &[],
-                            vec![Inlay {
-                                id: InlayId::InlineCompletion(post_inc(&mut next_inlay_id)),
-                                position: snapshot.buffer_snapshot.anchor_before(position),
-                                text: Rope::from(format!("Test inlay {next_inlay_id}")),
-                            }],
+                            vec![Inlay::inline_completion(
+                                post_inc(&mut next_inlay_id),
+                                snapshot.buffer_snapshot.anchor_before(position),
+                                format!("Test inlay {next_inlay_id}"),
+                            )],
                             cx,
                         );
                     }