editor: Improve code completion filtering to provide fewer and more accurate suggestions (#32928)

Closes #32756

- Uses `filter_text` from LSP source to filter items in completion list.
This fixes noisy lists like on typing `await` in Rust, it would suggest
`await.or`, `await.and`, etc., which are bad suggestions. Fallbacks to
label.
- Add `penalize_length` flag to fuzzy matcher, which was the default
behavior across. Now, this flag is set to `false` just for code
completion fuzzy matching. This fixes the case where if the query is
`unreac` and the completion items are `unreachable` and
`unreachable!()`, the item with a shorter length would have a larger
score than the other one, which is not right in the case of
auto-complete context. Now these two items will have the same fuzzy
score, and LSP `sort_text` will take over in finalizing its ranking.
- Updated test to be more utility based rather than example based. This
will help to iterate/verify logic faster on what's going on.

Before/After:

await: 
<img width="600" alt="before-await"
src="https://github.com/user-attachments/assets/384138dd-a90d-4942-a430-6ae15df37268"
/>
<img width="600" alt="after-await"
src="https://github.com/user-attachments/assets/d05a10fa-bae5-49bd-9fe7-9933ff215f29"
/>

iter:
<img width="600" alt="before-iter"
src="https://github.com/user-attachments/assets/6e57ffe9-007d-4b17-9cc2-d48fc0176c8e"
/>
<img width="600" alt="after-iter"
src="https://github.com/user-attachments/assets/a8577a9f-dcc8-4fd6-9ba0-b7590584ec31"
/>

opt:
<img width="600" alt="opt-before"
src="https://github.com/user-attachments/assets/d45b6c52-c9ee-4bf3-8552-d5e3fdbecbff"
/>
<img width="600" alt="opt-after"
src="https://github.com/user-attachments/assets/daac11a8-9699-48f8-b441-19fe9803848d"
/>

Release Notes:

- Improved code completion filtering to provide fewer and more accurate
suggestions.

crates/fuzzy/src/strings.rs

@@ -117,6 +117,7 @@ pub async fn match_strings<T>(
     candidates: &[T],
     query: &str,
     smart_case: bool,
+    penalize_length: bool,
     max_results: usize,
     cancel_flag: &AtomicBool,
     executor: BackgroundExecutor,
@@ -160,8 +161,13 @@ where
                 scope.spawn(async move {
                     let segment_start = cmp::min(segment_idx * segment_size, candidates.len());
                     let segment_end = cmp::min(segment_start + segment_size, candidates.len());
-                    let mut matcher =
-                        Matcher::new(query, lowercase_query, query_char_bag, smart_case);
+                    let mut matcher = Matcher::new(
+                        query,
+                        lowercase_query,
+                        query_char_bag,
+                        smart_case,
+                        penalize_length,
+                    );
 
                     matcher.match_candidates(
                         &[],