…h#17186)

Summary
--

Detects duplicate attributes in a `match` class pattern:

```python
match x:
    case Class(x=1, x=2): ...
```

which are more analogous to the similar check for mapping patterns than
to the
multiple assignments rule.

I also realized that both this and the mapping check would only work on
top-level patterns, despite the possibility that they can be nested
inside other
patterns:

```python
match x:
    case [{"x": 1, "x": 2}]: ...  # false negative in the old version
```

and moved these checks into the recursive pattern visitor instead.

I also tidied up some of the names like the `multiple_case_assignment`
function
and the `MultipleCaseAssignmentVisitor`, which are now doing more than
checking
for multiple assignments.

Test Plan
--

New inline tests for both classes and mappings.

* main:
  [red-knot] Empty tuple is always-falsy (#17213)
  Run fuzzer with `--preview` (#17210)
  Bump 0.11.4 (#17212)
  [syntax-errors] Allow `yield` in base classes and annotations (#17206)
  Don't skip visiting non-tuple slice in `typing.Annotated` subscripts (#17201)
  [red-knot] mypy_primer: do not specify Python version (#17200)
  [red-knot] Add `Type.definition` method (#17153)
  Implement `Invalid rule provided` as rule RUF102 with `--fix` (#17138)
  [red-knot] Add basic on-hover to playground and LSP (#17057)
  [red-knot] don't remove negations when simplifying constrained typevars (#17189)
  [minor] Fix extra semicolon for clippy (#17188)
  [syntax-errors] Invalid syntax in annotations (#17101)
  [syntax-errors] Duplicate attributes in match class pattern (#17186)
  [syntax-errors] Fix multiple assignment for class keyword argument (#17184)
  use astral-sh/cargo-dist instead (#17187)
  Enable overindented docs lint (#17182)