[no-restricted-path] Custom error message

[malykhinvi]

Main change
Adds a message configuration param for every zone, that will be displayed in case of the rule violation.
The logic is pretty similar to eslint's no-restricted-imports

Background
Sometimes, it is not very clear, why you can not import certain modules in certain scenarios. This is especially the case for newcomers. To be more user friendly, we could display additional info, right in the error message. It would look something like this:

//eslint config
'import/no-restricted-paths': [
  'error',
  {
    basePath: './src',
    zones: [ {
      target: './core',
      from: './features',
      message: '' +
        '\n\nCore should be completely isolated from features.' +
        '\nFeatures may use core but not vice versa',
    }],
  }
],

Then VSCode would display it like that:

[coveralls]

Coverage remained the same at 97.708% when pulling 0b81052 on malykhinvi:no-resticted-path-custom-message into 0b585a1 on benmosher:master.

[coveralls]

Coverage remained the same at 97.739% when pulling 7b5e2dc on malykhinvi:no-resticted-path-custom-message into 0547c7e on benmosher:master.

[coveralls]

Coverage remained the same at 97.739% when pulling 7b5e2dc on malykhinvi:no-resticted-path-custom-message into 0547c7e on benmosher:master.

[coveralls]

Coverage remained the same at 97.739% when pulling 7b5e2dc on malykhinvi:no-resticted-path-custom-message into 0547c7e on benmosher:master.

[ljharb]

Straightforward, looks good. Thanks!