ember-attacher 2.0

Quick Summary

ember-popper was replaced by the Floating UI
ember edition was changed to "octane"
ember-test-waiters are used now to wait until positioning inside requestAnimationFrame happen in tests
we dropped support for node < 12 and ember-source < 3.16

instead of popper modifiers you should use Floating UI middleware. You can import the default ones (like offset or flip) directly from @floating-ui/dom

For example
```
const modifiers = { offset: { offset: 10 } };
```
will become
```
import { offset } from '@floating-ui/dom';
...
const middleware = [offset(10)]
```
popperContainer is floatingElementContainer now
popperOptions is floatingUiOptions now. The object is passed to Floating UI computePosition function.
popperTarget is explicitTarget now.
Instead of registerAPI used to update your tooltip or popover manually, you should use autoUpdate option. It adds listeners that will automatically call an update function when necessary (if the user scrolls or resizes the screen, etc.).
For more details see Floating UI migration guide. Pay attention that ember-attacher v1 used Popper v1.

The prefix for the default floating element's id is now "-floating" instead of "-popper".
The default ember-attacher-popper class is now ember-attacher-floating

For Ember.js below the v3.20 you may need to install @ember/render-modifiers (ember install @ember/render-modifiers).

The addon may work with the ember-source < 3.16, yet the support is not guaranteed.