Avoid omitting optional parentheses for argument-less parentheses (#6484)

## Summary

This PR fixes some misformattings around optional parentheses for
expressions.

I first noticed that we were misformatting this:

```python
return (
    unicodedata.normalize("NFKC", s1).casefold()
    == unicodedata.normalize("NFKC", s2).casefold()
)
```

The above is stable Black formatting, but we were doing:
```python
return unicodedata.normalize("NFKC", s1).casefold() == unicodedata.normalize(
    "NFKC", s2
).casefold()
```

Above, the "last" expression is a function call, so our
`can_omit_optional_parentheses` was returning `true`...

However, it turns out that Black treats function calls differently
depending on whether or not they have arguments -- presumedly because
they'll never split empty parentheses, and so they're functionally
non-useful. On further investigation, I believe this applies to all
parenthesized expressions. If Black can't split on the parentheses, it
doesn't leverage them when removing optional parentheses.

## Test Plan

Nice increase in similarity scores.

Before:

- `zulip`: 0.99702
- `django`: 0.99784
- `warehouse`: 0.99585
- `build`: 0.75623
- `transformers`: 0.99470
- `cpython`: 0.75989
- `typeshed`: 0.74853

After:

- `zulip`: 0.99705
- `django`: 0.99795
- `warehouse`: 0.99600
- `build`: 0.75623
- `transformers`: 0.99471
- `cpython`: 0.75989
- `typeshed`: 0.74853

crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/split_empty_brackets.py

@@ -0,0 +1,90 @@
+# Expressions with empty parentheses.
+ct_match = (
+    unicodedata.normalize("NFKC", s1).casefold()
+    == unicodedata.normalize("NFKCNFKCNFKCNFKCNFKC", s2).casefold()
+)
+
+ct_match = (
+    unicodedata.normalize("NFKC", s1).casefold(1)
+    == unicodedata.normalize("NFKCNFKCNFKCNFKCNFKC", s2).casefold()
+)
+
+ct_match = (
+    unicodedata.normalize("NFKC", s1).casefold(0)
+    == unicodedata.normalize("NFKCNFKCNFKCNFKCNFKC", s2).casefold(1)
+)
+
+ct_match = (
+    unicodedata.normalize("NFKC", s1).casefold(1)
+    == unicodedata.normalize("NFKCNFKCNFKCNFKCNFKC", s2).casefold(1)
+)
+
+ct_match = (
+    unicodedata.normalize("NFKC", s1).casefold(
+        # foo
+    )
+    == unicodedata.normalize("NFKCNFKCNFKCNFKCNFKC", s2).casefold(
+        # foo
+    )
+)
+
+ct_match = (
+    [].unicodedata.normalize("NFKC", s1).casefold()
+    == [].unicodedata.normalize("NFKCNFKCNFKCNFKCNFKC", s2).casefold()
+)
+
+ct_match = (
+    [].unicodedata.normalize("NFKC", s1).casefold()
+    == [1].unicodedata.normalize("NFKCNFKCNFKCNFKCNFKC", s2).casefold()
+)
+
+ct_match = (
+    [1].unicodedata.normalize("NFKC", s1).casefold()
+    == [].unicodedata.normalize("NFKCNFKCNFKCNFKCNFKC", s2).casefold()
+)
+
+ct_match = (
+    [1].unicodedata.normalize("NFKC", s1).casefold()
+    == [1].unicodedata.normalize("NFKCNFKCNFKCNFKCNFKC", s2).casefold()
+)
+
+ct_match = (
+    {}.unicodedata.normalize("NFKC", s1).casefold()
+    == {}.unicodedata.normalize("NFKCNFKCNFKCNFKCNFKC", s2).casefold()
+)
+
+ct_match = (
+    {}.unicodedata.normalize("NFKC", s1).casefold()
+    == {1}.unicodedata.normalize("NFKCNFKCNFKCNFKCNFKC", s2).casefold()
+)
+
+ct_match = (
+    {1}.unicodedata.normalize("NFKC", s1).casefold()
+    == {}.unicodedata.normalize("NFKCNFKCNFKCNFKCNFKC", s2).casefold()
+)
+
+ct_match = (
+    {1}.unicodedata.normalize("NFKC", s1).casefold()
+    == {1}.unicodedata.normalize("NFKCNFKCNFKCNFKCNFKC", s2).casefold()
+)
+
+ct_match = (
+    ([]).unicodedata.normalize("NFKC", s1).casefold()
+    == ([]).unicodedata.normalize("NFKCNFKCNFKCNFKCNFKC", s2).casefold()
+)
+
+return await self.http_client.fetch(
+    f"http://127.0.0.1:{self.port}{path}", method=method, **kwargs,
+)
+
+return await self.http_client().fetch(
+    f"http://127.0.0.1:{self.port}{path}", method=method, **kwargs,
+)
+
+return await self().http_client().fetch(
+    f"http://127.0.0.1:{self.port}{path}", method=method, **kwargs,
+)
+
+response = await sync_to_async(
+    lambda: self.django_handler.get_response(request), thread_sensitive=True
+)()

crates/ruff_python_formatter/resources/test/fixtures/ruff/statement/assign.py

@@ -13,6 +13,17 @@ aa = [
     bakjdshflkjahdslkfjlasfdahjlfds
 ] = dddd = ddd = fkjaödkjaföjfahlfdalfhaöfaöfhaöfha = g = [3]
 
+aa = [
+
+] = dddd = ddd = fkjaödkjaföjfahlfdalfhaöfaöfhaöfha = g = [3]
+
+aa = [
+    # foo
+] = dddd = ddd = fkjaödkjaföjfahlfdalfhaöfaöfhaöfha = g = [3]
+
+aa = ([
+]) = dddd = ddd = fkjaödkjaföjfahlfdalfhaöfaöfhaöfha = g = [3]
+
 aaaa = ( # trailing
     # comment
     bbbbb) = cccccccccccccccc = 3