Fix run indicators jumping when buffer content changes. (#25507)

Co-authored-by: Anthony Eid <hello@anthonyeid.me>

Release Notes:

- Fix run indicators jumping when content changes

---------

Co-authored-by: Anthony Eid <hello@anthonyeid.me>

crates/editor/src/editor.rs

@@ -524,7 +524,7 @@ impl ScrollbarMarkerState {
 #[derive(Clone, Debug)]
 struct RunnableTasks {
     templates: Vec<(TaskSourceKind, TaskTemplate)>,
-    offset: MultiBufferOffset,
+    offset: multi_buffer::Anchor,
     // We need the column at which the task context evaluation should take place (when we're spawning it via gutter).
     column: u32,
     // Values of all named captures, including those starting with '_'
@@ -551,8 +551,6 @@ struct ResolvedTasks {
     templates: SmallVec<[(TaskSourceKind, ResolvedTask); 1]>,
     position: Anchor,
 }
-#[derive(Copy, Clone, Debug)]
-struct MultiBufferOffset(usize);
 #[derive(Copy, Clone, Debug, PartialEq, PartialOrd)]
 struct BufferOffset(usize);
 
@@ -10848,7 +10846,9 @@ impl Editor {
                     (runnable.buffer_id, row),
                     RunnableTasks {
                         templates: tasks,
-                        offset: MultiBufferOffset(runnable.run_range.start),
+                        offset: snapshot
+                            .buffer_snapshot
+                            .anchor_before(runnable.run_range.start),
                         context_range,
                         column: point.column,
                         extra_variables: runnable.extra_captures,