Migrate to new ESLint config file format

[nickrttn]

This is going to be the default configuration file format starting in ESLint v9.0.0, which is set to be released end of this year or beginning of next year.

[mifi]

can we use it with eslint 8?

[nickrttn]

Yes, it's been supported for a while now but not the default yet.

[mifi]

I just tested, but the problem is that eslint-config-airbnb doesn't support flat config yet. So I used the FlatCompat but as soon as I include the airbnb config, the eslint command just hangs forever.