message: chore: omit Observable from array prototype extension types
diff: -import Ember from 'ember';
  +import MutableArray from '@ember/array/mutable';
  +import Copyable from '@ember/object/-private/copyable';
  declare global {
  - interface Array<T> extends Ember.ArrayPrototypeExtensions<T> {}
  - // interface Function extends Ember.FunctionPrototypeExtensions {}
  + interface Array<T> extends MutableArray<T>, Copyable {}
  // Use Subclass<T> to allow abstract and non-abstract subclasses of T
  // Use ConcreteSubclass<T> to allow only non-abstract subclasses of T
  