Migrate to Babel 7.x

[php-coder]

This upgrade also should update transitive dependencies and resolve #1067, #1082 and #1296

Changelogs:

• https://babeljs.io/blog/2018/08/27/7.0.0
• https://babeljs.io/blog/2018/09/17/7.1.0
• https://babeljs.io/blog/2018/12/03/7.2.0
• https://babeljs.io/blog/2019/01/21/7.3.0
• https://babeljs.io/blog/2019/03/19/7.4.0
• https://babeljs.io/blog/2019/07/03/7.5.0
• https://babeljs.io/blog/2019/09/05/7.6.0
• https://babeljs.io/blog/2019/11/05/7.7.0
• https://babeljs.io/blog/2020/01/11/7.8.0
• https://babeljs.io/blog/2020/03/16/7.9.0
• https://babeljs.io/blog/2020/05/25/7.10.0

Could be useful:

• https://babeljs.io/docs/en/v7-migration
• https://github.com/babel/babel-upgrade
• https://medium.com/@maicmi/babel-upgrade-from-babel-6-x-to-7-0-58809bd63d8
• https://medium.com/@tonypai/fast-way-to-upgrade-to-babel-7-3f8cf97b4b3d
• https://stackoverflow.com/questions/52157996/how-to-upgrade-to-babel-7