Update webpack-dev-server configuration

[alexeyr-ci1]

1. Not all keys in https://webpack.js.org/configuration/dev-server/ are supported in

   shakapacker/package/environments/development.js

   Lines 17 to 41 in f5dfe4a

   	const devServerConfig = {
   	devMiddleware: {
   	publicPath
   	},
   	compress: devServer.compress,
   	allowedHosts: devServer.allowed_hosts,
   	host: devServer.host,
   	port: devServer.port,
   	https: devServer.https,
   	hot: devServer.hmr,
   	liveReload,
   	historyApiFallback: { disableDotRule: true },
   	headers: devServer.headers,
   	static: {
   	publicPath: contentBase
   	}
   	}
   	if (devServer.static) {
   	devServerConfig.static = { ...devServerConfig.static, ...devServer.static }
   	}
   	if (devServer.client) {
   	devServerConfig.client = devServer.client
   	}

   . Should we add support for the rest?
2. The recommended value for allowed_hosts is auto, not all which we have by default. It shouldn't be changed in a patch version, but maybe in 6.6.0 or 7.0.0?
3. https key on the Webpack side is deprecated in favor of server (which isn't currently supported on our side). Should we add support for it (even if we don't for other keys) and replace https in the default config?

[ahangarha]

@justin808 Please check this issue. Maybe we can add this to the version 7 milestone.

[justin808]

@ahangarha yes fix for 7.0

[ahangarha]

@justin808 I am working on this issue and I have some concerns.

I updated allowed_hosts and replaced https: false with server: http. These two changes are breaking ones, so the question is if we should provide backward compatibility? If yes, what is the best strategy?

I was also thinking if we could move this change to the next major release to reduce the number of breaking changes in version 7.

[ahangarha]

Done in #276