Update Babel dependencies

[homer0]

What does this PR do?

We are finally moving from Babel 6 to 7! So the big change on this PR is that everything Babel related now uses their "new" namespace: @babel/.

This is breaking because of two reasons:

1. If you have some custom plugin or something adding settings Babel configuration (or the env preset, like the Angular and React plugins), you need to update them to use the new name: @babel/preset-env.
2. If you added custom plugins or preset to your target Babel configuration, they now need to be compatible with Babel > 7, so they need to be on @babel/ (at least the officials).

How should it be tested manually?

1. Try enabling decorators or properties to your target and make sure they still work as expected.
2. And....

yarn test
# or
npm test

Don't try the other projext plugins yet as they are currently being updated too.

[coveralls]

Pull Request Test Coverage Report for Build 221

• 6 of 6 (100.0%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 100.0%

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Totals
Change from base Build 219:	0.0%
Covered Lines:	2028
Relevant Lines:	2028

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💛 - Coveralls