feat: add EyeTracker class

[josephine-funken]

Description

Added an EyeTracker class that can keep parsed eyetracker related data.

Fixes issue #597

Implemented changes

• [x] Create class EyeTracker
• [x] Use class in Experiment
• [x] Add short-access to Experiment.eye_tracker.sampling_rate from Experiment

Type of change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] This change is or requires a documentation update

How Has This Been Tested?

• [x] Test class tests.unit.gaze.eyetracker_test.py

Checklist:

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [ ] 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
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes
• [x] Any dependent changes have been merged and published in downstream modules
• [x] I have checked my code and corrected any misspellings

[codecov[bot]]

Codecov Report

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

Comparison is base (88b9af8) 100.00% compared to head (4ac9bee) 100.00%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #617 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 54 55 +1 Lines 2423 2463 +40 Branches 614 621 +7 ========================================= + Hits 2423 2463 +40 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[SiQube]

618 fixes the docs problems