Fixup comment handling on opening parenthesis in function definition (#6381)

## Summary

I noticed some deviations in how we treat dangling comments that hug the
opening parenthesis for function definitions.

For example, given:

```python
def f(  # first
    # second
):  # third
    ...
```

We currently format as:

```python
def f(
      # first
    # second
):  # third
    ...
```

This PR adds the proper opening-parenthesis dangling comment handling
for function parameters. Specifically, as with all other parenthesized
nodes, we now detect that dangling comment in `placement.rs` and handle
it in `parameters.rs`. We have to take some care in that file, since we
have multiple "kinds" of dangling comments, but I added a bunch of test
cases that we now format identically to Black.

## Test Plan

`cargo test`

Before:

- `zulip`: 0.99388
- `django`: 0.99784
- `warehouse`: 0.99504
- `transformers`: 0.99404
- `cpython`: 0.75913
- `typeshed`: 0.74364

After:

- `zulip`: 0.99386
- `django`: 0.99784
- `warehouse`: 0.99504
- `transformers`: 0.99404
- `cpython`: 0.75913
- `typeshed`: 0.74409

Meaningful improvement on `typeshed`, minor decrease on `zulip`.

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

@@ -295,3 +295,79 @@ def f(*args, b, **kwds, ): pass
 def f(*, b, **kwds, ): pass
 def f(a, *args, b, **kwds, ): pass
 def f(a, *, b, **kwds, ): pass
+
+# Handle comments on open parenthesis.
+def f(
+    # first
+    # second
+):
+    ...
+
+
+def f(  # first
+    # second
+):  # third
+    ...
+
+
+def f(  # first
+):  # second
+    ...
+
+
+def f(
+    a,
+    /,
+    # first
+    b
+    # second
+):
+    ...
+
+
+def f(  # first
+    *,
+    # second
+    b
+    # third
+):
+    ...
+
+
+def f(  # first
+    # second
+    *,
+    # third
+    b
+    # fourth
+):
+    ...
+
+
+def f(  # first
+    a,
+    # second
+):  # third
+    ...
+
+
+def f(  # first
+    a
+):  # second
+    ...
+
+
+def f(  # first
+    a
+    # second
+):  # third
+    ...
+
+
+def f(  # first
+    a,
+    / # second
+    ,
+    # third
+):
+    ...