Expand header_widget to include doc path, citation and help text

[K-Meech]

Description

What is this PR

• Bug fix
• 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 brainglobe/cellfinder#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:

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

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

Additional details and impacted files

@@            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     

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[K-Meech]

Example usage for cellfinder in this draft PR

[willGraham01]

Just a few minor docstring things, and technically PEP wants us to include the Optional keyword in the typehints (personally I still believe it's overkill but the PEP overlords have spoken).

[K-Meech]

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