feat(frontends/lean): 'override' command and '#<namespace> <expr>' notation also override aliases

Before this commit they were only overriding notation declarations.

src/frontends/lean/builtin_cmds.cpp

@@ -849,6 +849,7 @@ static environment override_cmd(parser & p) {
         ns = *real_ns;
         bool persistent = false;
         env = override_notation(env, ns, persistent);
+        env = overwrite_aliases(env, ns, name());
         env = update_fingerprint(env, ns.hash());
     }
     return env;

src/frontends/lean/builtin_exprs.cpp

@@ -564,6 +564,7 @@ static expr parse_override_notation(parser & p, unsigned, expr const *, pos_info
     name n = p.check_id_next("invalid '#' local notation, identifier expected");
     bool persistent = false;
     environment env = override_notation(p.env(), n, persistent);
+    env = overwrite_aliases(env, n, name());
     return p.parse_expr_with_env(env);
 }