Allow separate colour and size

[rcannood]

Describe your changes

• Allow specifying different columns in data for determining the colour and size of the geom using id_colour and id_size, respectively (Allow separate colour and size #25).

• Allow turning off bar outlines using draw_outline equal to FALSE for geom "bar" (Allow separate colour and size #25).

Issue ticket number and link

Closes #9
Closes #29

Checklist before requesting a review

• I have performed a self-review of my code

• Check the correct box. Does this PR contain:

  • Breaking changes
  • New functionality
  • Major changes
  • Minor changes
  • Bug fixes

• Proposed changes are described in the CHANGELOG.md

• CI Tests succeed and look good!

[rcannood]

In the end, I named the columns in column_info id_colour (or id_color) and id_size, because if I named them colour/color and size they might clash with already existing arguments and internal data. Will be merging this branch soon if no comments from @mxposed @LouiseDck @artuurC.

@lazappi I made a few more changes to make the figure produced by funkyheatmap more similar to the scib figure. Legends for images and bars are not supported yet (see #24 and #28, respectively), but I think the result is already a lot better. Let me know if you'd like to see other things changed.