Format Slice Expressions (#5047)

This formats slice expressions and subscript expressions.

Spaces around the colons follows the same rules as black
(https://black.readthedocs.io/en/stable/the_black_code_style/current_style.html#slices):
```python
e00 = "e"[:]
e01 = "e"[:1]
e02 = "e"[: a()]
e10 = "e"[1:]
e11 = "e"[1:1]
e12 = "e"[1 : a()]
e20 = "e"[a() :]
e21 = "e"[a() : 1]
e22 = "e"[a() : a()]
e200 = "e"[a() : :]
e201 = "e"[a() :: 1]
e202 = "e"[a() :: a()]
e210 = "e"[a() : 1 :]
```

Comment placement is different due to our very different infrastructure.
If we have explicit bounds (e.g. `x[1:2]`) all comments get assigned as
leading or trailing to the bound expression. If a bound is missing
`[:]`, comments get marked as dangling and placed in the same section as
they were originally in:
```python
x = "x"[ # a
      # b
    :  # c
      # d
]
```
to
```python
x = "x"[
    # a
    # b
    :
    # c
    # d
]
```
Except for the potential trailing end-of-line comments, all comments get
formatted on their own line. This can be improved by keeping end-of-line
comments after the opening bracket or after a colon as such but the
changes were already complex enough.

I added tests for comment placement and spaces.

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

@@ -0,0 +1,82 @@
+# Handle comments both when lower and upper exist and when they don't
+a1 = "a"[
+    # a
+    1  # b
+    :  # c
+    2  # d
+]
+a2 = "a"[
+    # a
+      # b
+    :  # c
+      # d
+]
+
+# Check all places where comments can exist
+b1 = "b"[ # a
+    # b
+    1 # c
+    # d
+    : # e
+    # f
+    2 # g
+    # h
+    : # i
+    # j
+    3 # k
+    # l
+]
+
+# Handle the spacing from the colon correctly with upper leading comments
+c1 = "c"[
+    1
+    :  # e
+    # f
+    2
+]
+c2 = "c"[
+    1
+    :  # e
+    2
+]
+c3 = "c"[
+    1
+    :
+    # f
+    2
+]
+c4 = "c"[
+    1
+    : # f
+    2
+]
+
+# End of line comments
+d1 = "d"[ # comment
+    :
+]
+d2 = "d"[  # comment
+    1:
+]
+d3 = "d"[
+    1  # comment
+    :
+]
+
+# Spacing around the colon(s)
+def a():
+    ...
+
+e00 = "e"[:]
+e01 = "e"[:1]
+e02 = "e"[: a()]
+e10 = "e"[1:]
+e11 = "e"[1:1]
+e12 = "e"[1 : a()]
+e20 = "e"[a() :]
+e21 = "e"[a() : 1]
+e22 = "e"[a() : a()]
+e200 = "e"[a() :: ]
+e201 = "e"[a() :: 1]
+e202 = "e"[a() :: a()]
+e210 = "e"[a() : 1 :]