Import header from brainglobe-utils

[K-Meech]

Description

What is this PR

• Bug fix
• Addition of a new feature
• Other

Why is this PR needed?
Currently, the brainreg widget has no header (i.e. no brainglobe logo / documentation links...).

What does this PR do?
This PR adds a header from brainglobe-utils. As this increases the length of an already long widget, a vertical scrollbar is also added to make navigation easier. This uses the same QScrollArea solution as the cellfinder detect and train widgets. These scrollbars aren't ideal as they require using internal (marked with _) values from the magicgui widget. A better solution would be to change all widgets to use qtpy directly, but this isn't a very quick fix.

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?

No

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

[adamltyson]

Thanks @K-Meech. I've raised an issue about converting to qtpy (#190).