Theme unhcr revision

[vidonne]

Review of the theme_unhcr function:

• Simplify function call and revert to some {ggplot2} default
• Implement {ggtext} package for title, subtitle and caption
• Add new arguments in the function to simplify customization
• Review some default values

Important changes:

• Some arguments are now deprecated (line_size, rel_small, rel_tiny, rel_large) and replaced by more specific argument like plot_title_size, plot_title_margin, etc.
• Implementation of {ggtext} requires to use <br> as a new line break instead of \n, but add a lot of flexibility for styling and your text will automatically stay within the box and not overlap. See ggtext::element_textbox_simple for more information.
• theme_unhcr_map function has been removed and replaced by the void argument in the theme_unhcr function.
• The conditional them for the tag has been removed. tag is still stylized the right way but we recommend you use your Rmd or qmd file to handle figure number.

Will fix #23 and #21

[dickoa]

Hi @vidonne It looks good to me, we just need to find a solution to not have the plot.background outline either via its color or linewidth.

[vidonne]

Finally took your approach of applying the plot_background value to color argument. This will avoid user confusion if they try to change the border color and we used the linewidth argument they still won't see any border as the linewidth would be 0.