basic formatting for ExprDict (#5167)

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

@@ -0,0 +1,50 @@
+# before
+{  # open
+ key# key
+ : # colon
+ value# value
+} # close
+# after
+
+
+{**d}
+
+{**a, #  leading
+** # middle
+b # trailing
+}
+
+{
+** # middle with single item
+b
+}
+
+{
+    # before
+    ** # between
+    b,
+}
+
+{
+    **a # comment before preceeding node's comma
+ ,
+    # before
+    ** # between
+    b,
+}
+
+{}
+
+{1:2,}
+
+{1:2,
+ 3:4,}
+
+{asdfsadfalsdkjfhalsdkjfhalskdjfhlaksjdfhlaskjdfhlaskjdfhlaksdjfh: 1, adsfadsflasdflasdfasdfasdasdf: 2}
+
+mapping = {
+    A: 0.25 * (10.0 / 12),
+    B: 0.1 * (10.0 / 12),
+    C: 0.1 * (10.0 / 12),
+    D: 0.1 * (10.0 / 12),
+}