feat: add new dataset GazeGraph

[prassepaul]

Description

Add new dataset: GazeGraph

Type of change

• [x] New feature (non-breaking change which adds functionality)

How Has This Been Tested?

Checklist:

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

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (d666422) 100.00% compared to head (8a5a622) 100.00%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #619 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 52 53 +1 Lines 2352 2376 +24 Branches 590 597 +7 ========================================= + Hits 2352 2376 +24 ``` | [Files](https://app.codecov.io/gh/aeye-lab/pymovements/pull/619?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aeye-lab) | Coverage Δ | | |---|---|---| | [src/pymovements/datasets/\_\_init\_\_.py](https://app.codecov.io/gh/aeye-lab/pymovements/pull/619?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aeye-lab#diff-c3JjL3B5bW92ZW1lbnRzL2RhdGFzZXRzL19faW5pdF9fLnB5) | `100.00% <100.00%> (ø)` | | | [src/pymovements/datasets/gaze\_graph.py](https://app.codecov.io/gh/aeye-lab/pymovements/pull/619?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=aeye-lab#diff-c3JjL3B5bW92ZW1lbnRzL2RhdGFzZXRzL2dhemVfZ3JhcGgucHk=) | `100.00% <100.00%> (ø)` | |

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