Implement the rest of the worktree pulls (#32269)

Follow-up of https://github.com/zed-industries/zed/pull/19230

Implements the workspace diagnostics pulling, and replaces "pull
diagnostics every open editors' buffer" strategy with "pull changed
buffer's diagnostics" + "schedule workspace diagnostics pull" for the
rest of the diagnostics.

This means that if the server does not support the workspace diagnostics
and does not return more in linked files, only the currently edited
buffer has its diagnostics updated.

This is better than the existing implementation that causes a lot of
diagnostics pulls to be done instead, and we can add more heuristics on
top later for querying more diagnostics.

Release Notes:

- N/A

crates/language/src/buffer.rs

@@ -126,8 +126,6 @@ pub struct Buffer {
     has_unsaved_edits: Cell<(clock::Global, bool)>,
     change_bits: Vec<rc::Weak<Cell<bool>>>,
     _subscriptions: Vec<gpui::Subscription>,
-    /// The result id received last time when pulling diagnostics for this buffer.
-    pull_diagnostics_result_id: Option<String>,
 }
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
@@ -956,7 +954,6 @@ impl Buffer {
             completion_triggers_timestamp: Default::default(),
             deferred_ops: OperationQueue::new(),
             has_conflict: false,
-            pull_diagnostics_result_id: None,
             change_bits: Default::default(),
             _subscriptions: Vec::new(),
         }
@@ -2763,14 +2760,6 @@ impl Buffer {
     pub fn preserve_preview(&self) -> bool {
         !self.has_edits_since(&self.preview_version)
     }
-
-    pub fn result_id(&self) -> Option<String> {
-        self.pull_diagnostics_result_id.clone()
-    }
-
-    pub fn set_result_id(&mut self, result_id: Option<String>) {
-        self.pull_diagnostics_result_id = result_id;
-    }
 }
 
 #[doc(hidden)]