This patch does the following:
1. Run the same prefixset tests when
* browser.safebrowsing.prefixset.max_array_size = 0
* browser.safebrowsing.prefixset.max_array_size = UINT32_MAX
This makes sure both of the methods to store prefixset are tested by existing testcases
2. Refine gtest with test fixture
3. Add TinySet and LargeSet testcases
Differential Revision: https://phabricator.services.mozilla.com/D30338