E0323 needs to be updated to new format

[sophiajt]

From: src/test/compile-fail/impl-wrong-item-for-trait.rs

Error E0323 needs a span_label, updated title, and a note, updating it from:

error[E0323]: item `bar` is an associated const, which doesn't match its trait `<FooConstForMethod as Foo>`
  --> src/test/compile-fail/impl-wrong-item-for-trait.rs:22:5
   |
22 |     const bar: u64 = 1;
   |     ^^^^^^^^^^^^^^^^^^^

To:

error[E0323]: item `bar` is an associated const, which doesn't match its trait
  --> src/test/compile-fail/impl-wrong-item-for-trait.rs:22:5
   |
22 |     const bar: u64 = 1;
   |     ^^^^^^^^^^^^^^^^^^^ does not match trait
   |
   = note: matching trait `<FooConstForMethod as Foo>`

Bonus: show the original part of the trait that conflicts:

error[E0323]: item `bar` is an associated const, which doesn't match its trait
  --> src/test/compile-fail/impl-wrong-item-for-trait.rs:22:5
   |
14 |    fn bar(&self);
   |    -------------- original trait requirement
...
22 |     const bar: u64 = 1;
   |     ^^^^^^^^^^^^^^^^^^^ does not match trait
   |
   = note: matching trait `<FooConstForMethod as Foo>`