fix: specifier subpath parse error

[stormslowly]

this case was found by web-infra-dev/rspack#10127

  × Module not found: Can't resolve 'webpack/hot/emitter.js' in '/Users/bytedance/git/problem/pnp-repro/.yarn/__virtual__/webpack-dev-server-virtual-e3e5db5beb/0/cache/webpack-dev-server-npm-5.2.0-baf75bbb61-87b7acc194.zip/node_modules/webpack-dev-server/client'
    ╭─[46:23]
 44 │ /* global __resourceQuery, __webpack_hash__ */ /// <reference types="webpack/module" />
 45 │ import webpackHotLog from "webpack/hot/log.js";
 46 │ import hotEmitter from "webpack/hot/emitter.js";
    ·                        ────────────────────────
 47 │ import socket from "./socket.js";
 48 │ import { formatProblem, createOverlay } from "./overlay.js";
    ╰────

root cause

calling parse_bare_identifier with webpack/hot/emitter.js
expect returns ("webpack", Some("hot/emitterjs"))
actual returns ("webpack", Some("hot"))