ESM support + Easier way to specify translationKeyMatcher

[bleuscyther]

New command --translation-key-matcher

This makes it easier to modify the matcher for more libraries like i18n-node, who use __ :

ESM module configuration file

When creating the configuration file from inside an ES-Modules (esm) the parser is not able to read the Common-js module without the .cjs extension.

To fix that we could use a .json configuration file without the support for callbacks or a .cjs file.

i18n-unused.config.json :

{
  "localesPath": "src/locales",
  "srcPath": "src",
  "translationKeyMatcher": "/(?:[$ .](_|t|tc|i18nKey|__))\\(.*?\\)/gi"
}

i18n-unused.config.cjs :

module.exports = {
  localesPath: 'src/locales',
  srcPath: 'src',
  translationKeyMatcher: /(?:[$ .](_|t|tc|i18nKey|__))\(.*?\)/gi
};

closes #30

[mxmvshnvsk]

Hi, thank you for wonder pr)

[bleuscyther]

You are welcome