fix: resolve issues with scoped classes in PHAR

[weierophinney]

This patch makes several changes to PHAR creation to resolve the following issues:

• Generated local configuration files were receiving the autogenerated namespace as a prefix to the configuration. This is likely a bug in Box and/or PHP-Scoper, but it's possible to work around it (I chose implode() with a list of lines, as any nowdoc or heredoc triggered the injection for me).

• Configuration files reference provider classes. This led to problems when scoping as those classes then could not be found. I have added php-scoper whitelist entries for the specified classes to ensure that configuration can be used and not lead to errors.

• Once php-scoper configuration was introduced, I started seeing warnings thrown around polyfill classes we use. I have updated the php-scoper configuration to whitelist global classes.

In my local testing, all operations that previously did not work under the PHAR now work.

Fixes #81 Fixes #82

[rieschl]

I can also confirm; it works now locally with the PHAR from 2.9.x. Thanks!