Add strict option to babel-plugin-transform-inline-environment-variables

The plugin already supports the `include` option, which will only transform the mentioned items.
To enforce, that no one tries to use names not specified in `include` I suggest to use a new option `strict` which throws an error if a name not specified in the `include` option is found.

Start by locating babel-plugin-transform-inline-environment-variables and its handling of the include option. Add coverage for strict behavior: names absent from include should raise an error, while names listed in include should continue to transform normally.

Written by the indexing model from the issue text.