feat: Add suffix 'config' to config filename

[regseb]

This PR adds the stryker.config.{json,js,mjs,cjs} and .stryker.config.{json,js,mjs,cjs} in the default config file names.

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For configuration files, the extension .config.js is often used. The extension .conf.js is less common. Here are examples of different projects that use .config.js: eslint.config.js, prettier.config.{js,cjs} (via Cosmiconfig), jest.config.{js,ts,mjs,cjs,json}, nyc.config.js, webpack.config.js, vue.config.js, next.config.{js,mjs}, docusaurus.config.js, stylelint.config.{cjs,js}, tailwind.config.js (via Lilconfig), typedoc.config.{js,cjs}.

	".config.js"	".conf.js"
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I propose this pull request because when creating a new project, I named my configuration files *.config.js (eslint.config.js, stylelint.config.js...). But when running Stryker, it couldn't find its configuration file, even though the .stryker.config.js file was present in the root of my project 🤔.

[nicojs]

I agree that .config.js is the better suffix. The .conf.js suffix is one of the last remnants of our karma past (we used to support only karma, and karma uses karma.conf.js).

• Should we also generate stryker.config.mjs and stryker.config.json by default during stryker init?
• Could you change 1 or more e2e tests to use stryker.config.js?
• Do you also want to create the PR to include stryker.config.[mjs,cjs,js,json] to https://github.com/vscode-icons/vscode-icons?

[regseb]

I've pushed a new commit https://github.com/regseb/stryker-js/commit/1819a2e8f758de5688f548e80ea4a8f3640ea58f, but it doesn't display in this pull request.

• master...regseb:stryker-js:config: 2 commits / 24 files changed / 1 contributor
• https://github.com/regseb/stryker-js/tree/config: This branch is 2 commits ahead, 7 commits behind stryker-mutator:master.

I don't know why it doesn't add in this pull request?

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I create pull request in vscode-icons/vscode-icons#3309

[nicojs]

I think it looks great so far.

However, I wonder if I would want to merge this before vscode-icons/vscode-icons#3309 is resolved. I would hate for users to have to look at the default JSON icon, when they have the fancy Stryker icon now.

[robertohuertasm]

However, I wonder if I would want to merge this before vscode-icons/vscode-icons#3309 is resolved. I would hate for users to have to look at the default JSON icon, when they have the fancy Stryker icon now.

FYI, v12.5.0 has been already published.