Expand support for KSyntaxHighlighting (Kate, KWrite, KDevelop...) themes

[luisbocanegra]

Is your feature request related to a problem? Please describe.
Apps that make use of KSyntaxHighlighting > KTextEditor (Kate, KWrite, KDevelop...) look very out of place since they only iterate between predefined Breeze themes by depending if the current theme is light or dark.

Describe the solution you'd like
It would be nice to also generate syntax-highlighting themes for those apps

Describe alternatives you've considered
None

Additional context

• syntax-highlighting should be located in ~/.local/share/org.kde.syntax-highlighting/themes/
• Theme's file structure (JSON) is explained in Working with Color Themes

Tasks:

• Theme basic properties (current line, selection, background, line numbers, error mark, warn mark)
• Theme rest of properties
• Check if it's possible to dynamically reload KSyntaxHighlighting themes

[luisbocanegra]

Very basic support has been added in e49b322