Bump `@hashicorp/ember-flight-icon` dependency to `3.0.0`

Description

We've released version 3.0.0 of @hashicorp/ember-flight-icon (and with it version 2.11.0 of @hashicorp/flight-icons).

In that release we have introduced an error message in console when the user sets a non-existing @name value for a FlightIcon. Since now it's used in Structure, we want to update the dependencies to include these changes.

Changes

In this PR I have:

bumped @hashicorp/ember-flight-icons to version 3.0.0
- @hashicorp/flight-icons has also been bumped by yarn to version 2.11.0
bumped ember-auto-import version (or it would throw an error at compilation/build time)
- Error received: To use these addons, your app needs ember-auto-import >= 2: @hashicorp/ember-flight-icons, @hashicorp/ember-flight-icons
added webpack as dev-dependency (or it would throw an error at compilation/build time)
- Error received: [ember-auto-import] this version of ember-auto-import requires the app to have a dependency on webpack 5

Testing

This PR will be tested together with #127 before actually releasing a new (breaking/major) version of Structure, and update it in Cloud UI.

hashicorp / structure