Add test for symbolification pipeline, based on test in Sentry repo

[emmatyping]

Arpad suggested for testing symbolicator workflows:

That seems like a good idea, yes. To cover this particular usecase, you would need a test that uses all the builtin symbol servers. A Windows minidump perhaps. We should have one already in the main Sentry tests, though those tests are always testing the very latest symbolicator master.

The tests live here: https://github.com/getsentry/sentry/tree/master/tests/symbolicator