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

crates/language/src/language_settings.rs

@@ -1045,6 +1045,15 @@ pub struct LanguageTaskConfig {
     pub variables: HashMap<String, String>,
     #[serde(default = "default_true")]
     pub enabled: bool,
+    /// 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)
+    #[serde(default = "default_true")]
+    pub prefer_lsp: bool,
 }
 
 impl InlayHintSettings {