Expand header_widget to include doc path, citation and help text

[K-Meech]

Description

What is this PR

• [ ] Bug fix
• [X] Addition of a new feature
• [ ] Other

Why is this PR needed? The header_widget currently doesn't support some of the required features for existing brainglobe headers like cellfinder and brainrender-napari

What does this PR do? This PR adds new features to the header_widget:

• Makes tutorial links optional
• Adds option for documentation links
• Adds option for citation doi
• Adds option for help text
• Adds option for github repo name (if not the same as the package name)

References

For https://github.com/brainglobe/cellfinder/issues/327

How has this PR been tested?

All tests pass locally.

Is this a breaking change?

No

Does this PR require an update to the documentation?

Relevant docstrings have been updated.

Checklist:

• [X] The code has been tested locally
• [X] Tests have been added to cover all new functionality (unit & integration)
• [X] The documentation has been updated to reflect any changes
• [X] The code has been formatted with pre-commit

[codecov[bot]]

Codecov Report

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

Project coverage is 90.70%. Comparing base (17e5ebc) to head (3556a72). Report is 2 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #70 +/- ## ========================================== + Coverage 89.07% 90.70% +1.62% ========================================== Files 35 35 Lines 1355 1377 +22 ========================================== + Hits 1207 1249 +42 + Misses 148 128 -20 ```

:umbrella: View full report in Codecov by Sentry.
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[K-Meech]

Example usage for cellfinder in this draft PR

[K-Meech]

All fixed now @willGraham01 ! Hopefully the PEP overlords are satisfied :laughing:. Feel free to merge if you're happy with it