Fixes the implementation of HMR

[homer0]

What does this PR do?

These changes apply when the target hot setting is true:

• It adds the NamedModulesPlugin plugin.
• Instead of configuring only the webpack-hot-middleware, it now checks if the target will run in order to configure the dev server or the middleware.
• If the target uses the babel-polyfill, it now makes sure the HMR entries are added after it and not just on top of the list.

Before this change, it wasn't possible for a target to use HMR on the dev server.

How should it be tested manually?

yarn test
# or
npm test

[coveralls]

Pull Request Test Coverage Report for Build 10

• 17 of 17 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 7:	0.0%
Covered Lines:	391
Relevant Lines:	391

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💛 - Coveralls

[homer0]

☠️