.eslintrc doesn't override defaults

First of all, thank you for the great tool!

Current Behavior

tsdx ignores .eslintrc.js or .eslintrc.json in project’s root directory and uses default config when lint script is run. At the moment it is possible to redefine default linting config only by specifying necessary settings in eslint key inside package.json. It is quite inconvenient.

Desired Behavior

Use .eslintrc.js or .eslintrc.json when it is present in project’s root directory to redefine/replace default config.

Suggested Solution

Check presence of .eslintrc.js or .eslintrc.json in project’s root directory and use its contents instead of default config returned by createEslintConfig.

Who does this impact? Who is this for?

All users wanting to customize linting settings.

Describe alternatives you’ve considered

Additional context

[gamtiq]

Sorry, I missed #498 (I searched only for open issues). I’ve added the following snippet in .eslintrc.js

    rules: {
        'prettier/prettier': 'off'
    }

as mentioned in the comment for 498 and fixed the problem.

By the way, I suppose the info from this comment (about You can change everything, but one difference with using an eslintrc file is that the internal rules will be added to any custom ones, unless you’ve specifically set them to off in your rules.) and this comment (adding 'prettier/prettier': 'off' to rules) should be added into README.md to avoid confusion.

[agilgur5]

it’d be a lot easier if the ESLint API handled it, but idk that it does.

Seems like there might be a way to hack it together with CLIEngine#getConfigForFile, but there isn’t really an exact API to check for existence of config, so I might have to file an issue with ESLint