Add support for Babel v8

# Support for Babel 8

## Description

`ember-cli-babel` currently does not support Babel 8.

When upgrading a project to Babel 8, `ember-cli-babel` is unable to work correctly with the new Babel version, preventing applications from upgrading their Babel dependencies.

## Expected behavior

`ember-cli-babel` should support Babel 8 and allow Ember applications to use the latest Babel release without requiring compatibility workarounds or pinning Babel to an older major version.

## Actual behavior

Using Babel 8 with `ember-cli-babel` results in compatibility issues because `ember-cli-babel` currently relies on Babel APIs and/or behavior that changed in Babel 8.

## Motivation

Babel 8 is a new major release with breaking changes, and projects upgrading their Babel dependencies will eventually need `ember-cli-babel` to support it.

It would be useful to add Babel 8 support and update any affected Babel APIs, dependencies, or compatibility checks.

## Additional context

This may also require reviewing `ember-cli-babel`'s Babel-related dependencies and peer dependency constraints to ensure Babel 8 is correctly supported.

Start by reviewing ember-cli-babel's Babel-related dependencies, peer dependency constraints, and compatibility checks, then identify the Babel APIs or behaviors that changed in Babel 8. Done means Ember applications can use Babel 8 without compatibility workarounds or pinning an older Babel version.

Written by the indexing model from the issue text.