Add test case for Preferences Activity

[FlyingPumba]

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This PR adds an Espresso test case for the Preferences Activity. It also includes three auxiliary classes with two custom Matchers and one custom ViewAction.

The test case was automatically generated using the ETG tool, which aims to achieve high activity coverage. In particular, this Espresso test increases the current overall coverage in the project by 1.48%.

Although this contribution was automatically generated, the code in this PR was manually reviewed to adhere to the project's contributing guidelines.

[FlyingPumba]

Hi @daniele-athome ! We haven't received a response yet for this PR. We would greatly appreciate if you can provide us any type of feedback.