Add Tests for `relic.sga` Module

[ModernMAK]

• [ ] Implement relic.sga.common.py Tests
• [ ] Implement relic.sga.hierarchy.py Tests
• [x] #13
• [x] #11
• [ ] Implement relic.sga.file.file.py Tests
• [x] #15
• [ ] Implement relic.sga.folder.folder.py Tests
• [ ] Implement relic.sga.folder.header.py Tests
• [ ] Implement relic.sga.toc.toc.py Tests
• [ ] Implement relic.sga.toc.toc_headers.py Tests
• [ ] Implement relic.sga.toc.toc_ptr.py Tests
• [ ] Implement relic.sga.vdrive.vdrive.py Tests
• [ ] Implement relic.sga.vdrive.virtual_drive.py Tests

Sub-Issue of #4