method-resolution: emit error for method calls with illegal Sized bound

  Resolves a FIXME at hir-ty/src/method_resolution.rs:151 in
  lookup_method_including_private that previously allowed calls
  like `x.cant_call()` on a `&dyn Foo` receiver to type-check
  without diagnostic when `cant_call(&self) where Self: Sized`,
  even though the `Self: Sized` predicate cannot be satisfied
  by the trait object.

  The existing predicates_require_illegal_sized_bound check in
  confirm.rs already correctly identifies this case (it iterates
  elaborated predicates and looks for `Self: Sized` clauses with
  a `TyKind::Dynamic` self type).  Adds an
  InferenceDiagnostic::MethodCallIllegalSizedBound variant,
  plumbs the cooked diagnostic through hir, and renders it as
  RustcHardError E0277.

  Tests: trait-object call with Sized-bounded method errors;
  trait-object call to dyn-safe method does not; concrete-type
  call to a Sized-bounded method does not.

  Part of rust-lang/rust-analyzer#22140.

Signed-off-by: Onyeka Obi <softwareengineerasaservant@isurvivable.cv>