Add tests to coverage Browser::isDefaultBrowserHexCodeFound()
Add tests to coverage Browser::isDefaultBrowserHexCodeFound()

`isDefaultBrowserHexCodeFound()` method was added in https://github.com/pH7Software/pH7-Social-Dating-CMS/commit/9cf6a853bbef8957a684fba9ee4762778ae5a4ea#diff-bc8d4f3b291a478e370c201f6365b406 changes.

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