Enable clippy::never_loop (#9006)

Three changes: two of which are changing `while let` construct to `if
let` as they unconditionally broke and one of which was removing a loop
in the `start_default_prettier` as it unconditionally broke in the
control flow for match installation task: the diff for this is larger
than needed as removing the loop changed a lot of indentation for
`rustfmt`.

Cargo.toml

@@ -412,7 +412,6 @@ derive_ord_xor_partial_ord = "allow"
 eq_op = "allow"
 let_underscore_future = "allow"
 map_entry = "allow"
-never_loop = "allow"
 non_canonical_clone_impl = "allow"
 non_canonical_partial_ord_impl = "allow"
 reversed_empty_ranges = "allow"

crates/assistant/src/assistant_panel.rs

@@ -2094,7 +2094,7 @@ impl Conversation {
         let buffer = self.buffer.read(cx);
         let mut message_anchors = self.message_anchors.iter().enumerate().peekable();
         iter::from_fn(move || {
-            while let Some((start_ix, message_anchor)) = message_anchors.next() {
+            if let Some((start_ix, message_anchor)) = message_anchors.next() {
                 let metadata = self.messages_metadata.get(&message_anchor.id)?;
                 let message_start = message_anchor.start.to_offset(buffer);
                 let mut message_end = None;

crates/multi_buffer/src/multi_buffer.rs

@@ -1349,7 +1349,7 @@ impl MultiBuffer {
                     cursor.next(&());
 
                     // Skip over any subsequent excerpts that are also removed.
-                    while let Some(&next_excerpt_id) = excerpt_ids.peek() {
+                    if let Some(&next_excerpt_id) = excerpt_ids.peek() {
                         let next_locator = snapshot.excerpt_locator_for_id(next_excerpt_id);
                         if let Some(next_excerpt) = cursor.item() {
                             if next_excerpt.locator == *next_locator {
@@ -1358,7 +1358,6 @@ impl MultiBuffer {
                                 continue 'remove_excerpts;
                             }
                         }
-                        break;
                     }
 
                     break;

crates/project/src/prettier_support.rs

@@ -230,7 +230,6 @@ fn start_default_prettier(
     cx: &mut ModelContext<'_, Project>,
 ) -> Task<anyhow::Result<PrettierTask>> {
     cx.spawn(|project, mut cx| async move {
-        loop {
         let installation_task = project.update(&mut cx, |project, _| {
             match &project.default_prettier.prettier {
                 PrettierInstallation::NotInstalled {
@@ -292,7 +291,6 @@ fn start_default_prettier(
                 }
             },
         }
-        }
     })
 }