Add get_remote_fixture and get_remote_fixture_archive for tests

[ryanohoro]

Describe the change

This change adds two methods supporting scanner tests that allows fixtures to be loaded remotely via URL. Fixtures can be single files, or archive (with a password) so that malicious samples can be used to test scanners without committing them to the Strelka repo directly.

Describe testing procedures

Tested with a successful build.

Sample output

N/A

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of and tested my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings