Add the ability for tasks to target the center pane (#22004)

Closes #20060
Closes #20720
Closes #19873
Closes #9445

Release Notes:

- Fixed a bug where tasks would be spawned with their working directory
set to a file in some cases
- Added the ability to spawn tasks in the center pane, when spawning
from a keybinding:

```json5
[
  {
    // Assuming you have a task labeled "echo hello"
    "ctrl--": [
      "task::Spawn",
      { "task_name": "echo hello", "target": "center" }
    ]
  }
]
```

crates/project/src/task_inventory.rs

@@ -177,7 +177,7 @@ impl Inventory {
                 let id_base = kind.to_id_base();
                 Some((
                     kind,
-                    task.resolve_task(&id_base, task_context)?,
+                    task.resolve_task(&id_base, Default::default(), task_context)?,
                     not_used_score,
                 ))
             })
@@ -397,7 +397,7 @@ mod test_inventory {
             let id_base = task_source_kind.to_id_base();
             inventory.task_scheduled(
                 task_source_kind.clone(),
-                task.resolve_task(&id_base, &TaskContext::default())
+                task.resolve_task(&id_base, Default::default(), &TaskContext::default())
                     .unwrap_or_else(|| panic!("Failed to resolve task with name {task_name}")),
             );
         });

crates/project/src/task_store.rs

@@ -331,7 +331,7 @@ fn local_task_context_for_location(
     let worktree_id = location.buffer.read(cx).file().map(|f| f.worktree_id(cx));
     let worktree_abs_path = worktree_id
         .and_then(|worktree_id| worktree_store.read(cx).worktree_for_id(worktree_id, cx))
-        .map(|worktree| worktree.read(cx).abs_path());
+        .and_then(|worktree| worktree.read(cx).root_dir());
 
     cx.spawn(|mut cx| async move {
         let worktree_abs_path = worktree_abs_path.clone();

crates/project/src/terminals.rs

@@ -50,13 +50,7 @@ impl Project {
             .and_then(|entry_id| self.worktree_for_entry(entry_id, cx))
             .into_iter()
             .chain(self.worktrees(cx))
-            .find_map(|tree| {
-                let worktree = tree.read(cx);
-                worktree
-                    .root_entry()
-                    .filter(|entry| entry.is_dir())
-                    .map(|_| worktree.abs_path().clone())
-            });
+            .find_map(|tree| tree.read(cx).root_dir());
         worktree
     }