Skip over folded regions when iterating over multibuffer chunks (#15646)

This commit weaves through new APIs for language::BufferChunks, multi_buffer::MultiBufferChunks and inlay_map::InlayChunks that allow seeking with an upper-bound. This allows us to omit doing syntax highligting and looking up diagnostics for folded ranges. This in turn directly improves performance of assistant panel with large contexts.

Release Notes:

- Fixed poor performance when editing in the assistant panel after
inserting large files using slash commands

---------

Co-authored-by: Max <max@zed.dev>
Co-authored-by: Max Brunsfeld <maxbrunsfeld@gmail.com>

crates/editor/src/display_map/inlay_map.rs

@@ -225,14 +225,16 @@ pub struct InlayChunks<'a> {
 }
 
 impl<'a> InlayChunks<'a> {
-    pub fn seek(&mut self, offset: InlayOffset) {
-        self.transforms.seek(&offset, Bias::Right, &());
+    pub fn seek(&mut self, new_range: Range<InlayOffset>) {
+        self.transforms.seek(&new_range.start, Bias::Right, &());
 
-        let buffer_offset = self.snapshot.to_buffer_offset(offset);
-        self.buffer_chunks.seek(buffer_offset);
+        let buffer_range = self.snapshot.to_buffer_offset(new_range.start)
+            ..self.snapshot.to_buffer_offset(new_range.end);
+        self.buffer_chunks.seek(buffer_range);
         self.inlay_chunks = None;
         self.buffer_chunk = None;
-        self.output_offset = offset;
+        self.output_offset = new_range.start;
+        self.max_output_offset = new_range.end;
     }
 
     pub fn offset(&self) -> InlayOffset {