Take over the require cache within a test run

[MagiMaster]

Use loadmodule to have TestEZ manage the require cache for the tests it's running. This is doesn't do much on its own, but is needed for the monkey patching changes to be added later. Requires coming from the launcher script will no longer touch anything inside tests after this, so extraEnvironment will not work and global configuration will need to be done within init.spec.lua files.