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" }
    ]
  }
]
```

docs/src/tasks.md

@@ -155,6 +155,30 @@ You can define your own keybindings for your tasks via additional argument to `t
 }
 ```
 
+Note that these tasks can also have a 'target' specified to control where the spawned task should show up.
+This could be useful for launching a terminal application that you want to use in the center area:
+
+```json
+// In tasks.json
+{
+  "label": "start lazygit",
+  "command": "lazygit -p $ZED_WORKTREE_ROOT"
+}
+```
+
+```json
+// In keymap.json
+{
+  "context": "Workspace",
+  "bindings": {
+    "alt-g": [
+      "task::Spawn",
+      { "task_name": "start lazygit", "target": "center" }
+    ]
+  }
+}
+```
+
 ## Binding runnable tags to task templates
 
 Zed supports overriding default action for inline runnable indicators via workspace-local and global `tasks.json` file with the following precedence hierarchy: