Expose ESLint's --format already.

[laino]

The default reporter lacks information compared to the output of (for example) the JSON reporter.

This makes linting in all IDEs using standard terrible by default.

I realize this has been discussed already, but the closing argument didn't make much sense, because

1. If there was any gatekeeping, it would be done by eslint
2. There is no gatekeeping because you can use custom formatters anyways.

I'm trying to modernize and improve the eslint linter in vim's ale right now by migrating it to JSON, but for now I have to keep the old code around just to keep this linter working.

The main feature that is missing with the default output is getting proper "endColumn" values.

[laino]

For illustrative purposes, here is linting without endColumn values:

And linting with endColumn values: