Add webpack hot-reload/cache plugins to improve Lens DX

[chenhunghan]

for better DX..

• Add webpack-dev-server/react-refresh/react-refresh-webpack-plugin for hot-reload support, and add condition (see here)to redirect static file requests (/LensDev.js/LensDev.html) to webpack-dev-server. React-refresh is experimental, but seems to work fine.
• Add type-fest for support of typescript for react-refresh-webpack-plugin according to its README.
• Add hard-source-webpack-plugin for caching both main and renderer, the caching will improve webpack re-pack speed (like the old webpack DLL plugin). Webpack 5 support this out-of--the-box so we should remove this when upgrade to Webpack 5.
• I tried to upgrade to Webpack 5 but failed, too many error regarding the plugins.

[ixrock]

Awesome! Seems to work fine and stable!

[aleksfront]

👏

[ixrock]

LGTM