As of #23867 this is now a real package, so updating the imports to
use the real package name, rather than relying on the alias. The
name change in the package name is because `I18n` is not a valid
name as NPM packages must be all lowercase.
This commit also introduces an eslint rule to prevent importing from
the old I18n path.
For themes/plugins, the old 'i18n' name remains functional.
We want to wrap the `Ember.run.debounce` function and internally call `Ember.run` instead when running tests.
This commit changes discourseDebounce to work the same way as `Ember.run.debounce`.
Now that `discourseDebounce` works exactly like `Ember.run.debounce`, let's replace it and only use `DiscourseDebounce` from now on.
Move debounce to discourse-common to be able to reuse it in different bundles
Keep old debounce file for backwards-compatibility
