Auto merge of #108324 - notriddle:notriddle/assoc-fn-method, r=compiler-errors,davidtwco,estebank,oli-obk

diagnostics: if AssocFn has self argument, describe as method

Discussed in 329265515

This commit also changes the tooltips on rustdoc intra-doc links targeting methods.

For anyone not sure why this is being done, see the Reference definitions of these terms in <https://doc.rust-lang.org/1.67.1/reference/items/associated-items.html#methods>

> Associated functions whose first parameter is named `self` are called methods and may be invoked using the [method call operator](https://doc.rust-lang.org/1.67.1/reference/expressions/method-call-expr.html), for example, `x.foo()`, as well as the usual function call notation.

In particular, while this means it's technically correct for rustc to refer to a method as an associated function (and there are a few cases where it'll still do so), rustc *must never* use the term "method" to refer to an associated function that does not have a `self` parameter.

compiler/rustc_hir_analysis/src/check/check.rs

@@ -1461,7 +1461,7 @@ fn opaque_type_cycle_error(
                                     span,
                                     format!(
                                         "{} captures itself here",
-                                        tcx.def_kind(closure_def_id).descr(closure_def_id)
+                                        tcx.def_descr(closure_def_id)
                                     ),
                                 );
                             }