Allow formatting selections via LSP (#18752)

Release Notes:

- Added a new `editor: format selections` action that allows formatting
only the currently selected text via the primary language server.

---------

Co-authored-by: Thorsten Ball <mrnugget@gmail.com>

crates/editor/src/editor.rs

@@ -122,7 +122,7 @@ use multi_buffer::{
 use ordered_float::OrderedFloat;
 use parking_lot::{Mutex, RwLock};
 use project::{
-    lsp_store::FormatTrigger,
+    lsp_store::{FormatTarget, FormatTrigger},
     project_settings::{GitGutterSetting, ProjectSettings},
     CodeAction, Completion, CompletionIntent, DocumentHighlight, InlayHint, Item, Location,
     LocationLink, Project, ProjectPath, ProjectTransaction, TaskSourceKind,
@@ -10386,13 +10386,39 @@ impl Editor {
             None => return None,
         };
 
-        Some(self.perform_format(project, FormatTrigger::Manual, cx))
+        Some(self.perform_format(project, FormatTrigger::Manual, FormatTarget::Buffer, cx))
+    }
+
+    fn format_selections(
+        &mut self,
+        _: &FormatSelections,
+        cx: &mut ViewContext<Self>,
+    ) -> Option<Task<Result<()>>> {
+        let project = match &self.project {
+            Some(project) => project.clone(),
+            None => return None,
+        };
+
+        let selections = self
+            .selections
+            .all_adjusted(cx)
+            .into_iter()
+            .filter(|s| !s.is_empty())
+            .collect_vec();
+
+        Some(self.perform_format(
+            project,
+            FormatTrigger::Manual,
+            FormatTarget::Ranges(selections),
+            cx,
+        ))
     }
 
     fn perform_format(
         &mut self,
         project: Model<Project>,
         trigger: FormatTrigger,
+        target: FormatTarget,
         cx: &mut ViewContext<Self>,
     ) -> Task<Result<()>> {
         let buffer = self.buffer().clone();
@@ -10402,7 +10428,9 @@ impl Editor {
         }
 
         let mut timeout = cx.background_executor().timer(FORMAT_TIMEOUT).fuse();
-        let format = project.update(cx, |project, cx| project.format(buffers, true, trigger, cx));
+        let format = project.update(cx, |project, cx| {
+            project.format(buffers, true, trigger, target, cx)
+        });
 
         cx.spawn(|_, mut cx| async move {
             let transaction = futures::select_biased! {