Improve LSP tasks ergonomics (#31551)

* stopped fetching LSP tasks for too long (but still use the hardcoded
value for the time being — the LSP tasks settings part is a simple bool
key and it's not very simple to fit in another value there)

* introduced `prefer_lsp` language task settings value, to control
whether in the gutter/modal/both/none LSP tasks are shown exclusively,
if possible

Release Notes:

- Added a way to prefer LSP tasks over Zed tasks

assets/settings/default.json

@@ -1314,7 +1314,17 @@
   // Settings related to running tasks.
   "tasks": {
     "variables": {},
-    "enabled": true
+    "enabled": true,
+    // Use LSP tasks over Zed language extension ones.
+    // If no LSP tasks are returned due to error/timeout or regular execution,
+    // Zed language extension tasks will be used instead.
+    //
+    // Other Zed tasks will still be shown:
+    // * Zed task from either of the task config file
+    // * Zed task from history (e.g. one-off task was spawned before)
+    //
+    // Default: true
+    "prefer_lsp": true
   },
   // An object whose keys are language names, and whose values
   // are arrays of filenames or extensions of files that should