* fix: Apply theme style to embedded diagram (#7903)
When diagrams are created with "adaptive colors" they automatically
change to light-/darkmode depending on the browser preference. This
leads to rendering problems when the settings in the browser differ
from the wiki.js theme setting.
Fixes#7677
* fix: Update color scheme for SVG in diagram class
Refactor SVG color scheme handling in diagram class.
* fix: remove duplicate svg first-child class
Removed unnecessary direction property from first SVG in diagram.
---------
Co-authored-by: Nicolas Giard <github@ngpixel.com>