chore(deps-dev): migrate to webpack-cli v4 & webpack-dev-server v4 轉移到 webpack-cli v4 & webpack-dev-server v4

[IepIweidieng]

This resolves #94 by upgrading webpack-dev-server to 4.0.0.
將 webpack-dev-server 升級爲 4.0.0 以修正 #94 的問題。

Since the aforementioned issue does not affect this version of webpack-dev-server, the workaround in #94 will be unnecessary if this PR is applied.
由於前述問題不影響此版本的 webpack-dev-server，套用此 PR 後將不再需要 #94 中所述的暫緩方案。

This PR is based on https://github.com/ccns/PttChrome/pull/5
此 PR 基於 https://github.com/ccns/PttChrome/pull/5

See commit messages for details.
詳見 commit 訊息。

[IepIweidieng]

This PR branch is updated to include the changes in robertabcd/PttChrome@7eff62e0aa3afaece222424d9fe03a93a233add0.

[IepIweidieng]

Fixed yarn.lock regression.