DRAFT: GEODE-8040: Make BootstrappingFunction unit testable

[kirklund]

No description provided.

[kirklund]

@jdeppe-pivotal do you have any ideas why any changes to BootstrappingFunction causes the Tomcat session tests in UpgradeTest to fail? I only made changes to BootstrappingFunction to enable it to be well unit tested, but after a week I still can't get it to pass. I'm reluctant to throw away the changes but I'm out of time. I moved BootstrappingFunctionTest to BootstrappingFunctionIntegrationTest because it creates a full Cache despite the use of Mockito. The when/thenReturn stubbing for the BootstrappingFunction spy is incorrect -- the test executes the real code and THEN returns the mockCache -- but the real code creates a real Cache that then isn't used.