refactor: improve overall repo structure

[AngryMaciek]

Checklist:

• [ ] My code follows the style guidelines of this project
• [ ] I have performed a self-review of my own code
• [ ] I have commented my code, particularly in hard-to-understand areas
• [ ] My changes generate no new warnings
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] New and existing unit tests pass locally with my changes

• [ ] I have not reduced the existing code coverage

[codecov[bot]]

Codecov Report

Patch and project coverage have no change.

Comparison is base (61ddc88) 100.00% compared to head (9f4fb2a) 100.00%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #61 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 2 2 Lines 893 893 ========================================= Hits 893 893 ``` | [Files Changed](https://app.codecov.io/gh/AngryMaciek/hypercomplex/pull/61?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Maciek+B%C4%85k) | Coverage Δ | | |---|---|---| | [hypercomplex/Hypercomplex.hpp](https://app.codecov.io/gh/AngryMaciek/hypercomplex/pull/61?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Maciek+B%C4%85k#diff-aHlwZXJjb21wbGV4L0h5cGVyY29tcGxleC5ocHA=) | `100.00% <ø> (ø)` | | | [hypercomplex/Polynomial.hpp](https://app.codecov.io/gh/AngryMaciek/hypercomplex/pull/61?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Maciek+B%C4%85k#diff-aHlwZXJjb21wbGV4L1BvbHlub21pYWwuaHBw) | `100.00% <ø> (ø)` | |

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