789 add tabular example in dashboard and more example upgrades

[laurasootes]

Builds on PR #838, so that one has to be approved first

This PR adds a number of things to the dashboard:

• Tabular regression example sunshine hours.
• Tabular classification example penguin identification. Fixes Add tabular example in dashboard #789
• sets for various examples in the dashboard the default parameters equal to those used in the example notebooks
• allows the user to change the text input for the movie example, as per dashboard: allow for own input in examples #835
• add the image of the original FRB signal to the example, to show it side by side with the explanation
• adds tests for the tabular examples
• fixes the timeout error for the dashboard test Tests for the dashboard #567
• fixes the rendering of the menu as top only when dianna-dashboard installation is used

[elboyran]

I see this is still present, is it needed? The other PR deemed this as a temp solution to setting the number classes.

[laurasootes]

yes I believe so, the temporary solution originates from pr #641 and is mentioned in issue #801, but has not been fixed. Once that is fixed, it can be fixed here.

[elboyran]

Nice work, @laurasootes !

[elboyran]

For fixing the conflicting files, consider the latest change

[elboyran]

To fix the DOI in #854.