SpringBoot Test in ExtractCommandTests does not write files to the project directory

This change fixes the ExtractCommandTests#runWithJarFileThatWouldWriteEntriesOutsideDestinationFails test to not write files to the project directory. This could cause issues with Gradle caching and up-to-date checks because some tasks depend on the project directory as an input (for example Checkstyle). See below:

To address this, I mocked the working directory to a temporary directory like all the other tests in this class.

Comment From: wilkinsona

Thanks very much, @erichaagdev.