fix: ensures cssReload is called on first import

[ferdinando-ferreira]

This PR contains a:

• bugfix
• new feature
• code refactor
• test update
• typo fix
• metadata update

Motivation / Use-Case

Hot module reload was never called on the first inclusion of a css file.

Breaking Changes

None

Additional Info

Fixes #706.

These are the steps to reproduce both the issue and the solution

Testing the problem

git clone https://github.com/ferdinando-ferreira/mini-css-extract-plugin-new-css-import.git --single-branch mini-css-extract-plugin-new-css-import
cd mini-css-extract-plugin-new-css-import
npm install

To test the problem, run

npm run start

The browser will open on localhost:8080. Then open `index.js´ and remove the comment from the following line

// import "./second.css";

• Expected result: font size of foo will increase to 48px
• Actual result: it doesn't

Testing the solution

To test the solution, restore `index.js* to the original state, and run

npm run start:fixed

The browser will open on localhost:8080. Then open `index.js´ and remove the comment from the following line

// import "./second.css";

• Expected result: font size of foo will increase to 48px
• Actual result: works as expected

[ferdinando-ferreira]

Caveat: cssReload() is called unnecessarily on first execution.

Considering it has no actual impact that could be a "lesser" bug than the original one (not being called on new import), one that I can fix given enough time and strictly if needed