Print stylesheets and WHCM improvements

[shyusu4]

This PR addresses styling issues related to print stylesheets and windows high contrast mode:

Print stylesheets

• Components with dark backgrounds arent rendered correctly in print. The text appears gray instead of black.
• Interactive content such as header navigation elements (search, menu toggle), sign-up forms, and videos should be hidden for print.
• In-line href attributes should be used in print so that users are aware of destination of each link.
• Only important iconography and images should be retained for print.

Most site visitors would likely want to print or save blog posts as PDFs compared to other pages on the site. You can see the difference between the blog post without print styles and the one with print styles.

WHCM #454

• Menu toggle isn't visible
• Close icon in the search modal isn’t visible
• Copy icon in "pip install Wagtail" button disappears when clicking on it.
• (not in audit) SVG icons in buttons now match the button text color

Screenshots

	forced-colors: active + prefers-color-scheme: dark	forced-colors: active + prefers-color-scheme: light

[thibaudcolas]

All looking good, thank you @shyusu4!

[thibaudcolas]

❤️

[thibaudcolas]

I think those kinds of overrides would be easier to manage in component stylesheets? As-is, I can see this getting out of date with other styles over time.