Rename all ParseSess variables/fields/lifetimes as psess.

Existing names for values of this type are `sess`, `parse_sess`,
`parse_session`, and `ps`. `sess` is particularly annoying because
that's also used for `Session` values, which are often co-located, and
it can be difficult to know which type a value named `sess` refers to.
(That annoyance is the main motivation for this change.) `psess` is nice
and short, which is good for a name used this much.

The commit also renames some `parse_sess_created` values as
`psess_created`.

compiler/rustc_interface/src/queries.rs

@@ -120,7 +120,7 @@ impl<'tcx> Queries<'tcx> {
 
             rustc_builtin_macros::cmdline_attrs::inject(
                 &mut krate,
-                &sess.parse_sess,
+                &sess.psess,
                 &sess.opts.unstable_opts.crate_attr,
             );