Test for environment variables of process contexts

[slskiba]

With PR #578 we have added the functionality to set the IDEA_PROPERTIES and STUDIO_PROPERTIES to the process context that starts intellij and androidstudio respectively, instead of writing their values to ide.properties files at installation and reading them again when running the tools.

We want to test for their presence in the respective intellij and androidstudio tests. There might be further tools setting environment variables at run time (e.g. due to evaluated dependencies), that may also be tested.

In order to test this, we would need to mock the ProcessContext, run the corresponding tool and then verify that the environment variable was set in the mocked ProcessContext.