Allow logging to be disabled

[gitKrystan]

You can now configure this addon under the 'ember-this-fallback' key in the EmberApp constructor options:

"use strict";

const EmberApp = require("ember-cli/lib/broccoli/ember-app");

module.exports = function (defaults) {
  const app = new EmberApp(defaults, {
    //...
    "ember-this-fallback": {
      /**
       * Disable all logging, including debug logging (even with the `DEBUG`
       * environment variable) and logging to `ember-this-fallback-plugin.log`.
       */
      enableLogging: false,
    },
  });
  // ...
};