Move ClockMock to tests

[uncaught]

Problem Statement

I've just had the mishap that my IDE imported your Sentry\Util\ClockMock instead of the intended Symfony\Bridge\PhpUnit\ClockMock and I didn't notice because it is the same content with the same methods.

I was really confused as to why the tests didn't work and it took a while before I noticed.

Solution Brainstorm

You don't seem to use ClockMock anywhere in src (rightfully so), so please move it into tests, which is not exposed when installing via composer.

Thank you.

[linear]

PHP-58

[Litarnus]

Hi @uncaught! Good idea, we will move it to tests