es6 module - hoist private module providers

[spalger]

Find all usage of Private(require('...')); and convert it into two things:

at the top/under the other imports of a file:

import ...Provider from '...';

replace the original statements with:

Private(...Provider);

[epixa]

Test failure

[spalger]

resubmitting from elastic:implement/es6Modules/privateProviders