Feature: Add Welcome Banner

[kjohnson]

Depends on https://github.com/impress-org/givewp-gateway-server/pull/20

Description

This PR introduces the Welcome Banner component for the NextGen feature plugin.

Visuals

Welcome Banner (screenshot)

Dismiss Action/Animation

Newsletter Subscribe Action/Animation

Responsive Design

Testing Instructions

• Dismiss the Welcome Banner using the "X"/Close at the top right.
• Reset the Welcome Banner by deleting the givewp_next_gen_welcome_banner_dismissed option.

[jdghinson]

Check the spacing between the "Next steps" and "Join the Journey", it's 12px in the design and also look at the spacing between these titles ("Join the journey" and "Create your new donation form") and their respective descriptions, it's also 12px in the design. The image looks like the spacing is more than that.

[kjohnson]

@jdghinson I updated the spacing around the headings, which had default margins added by the browser that I updated.

[JasonTheAdams]

Let's hold on merging this until I get the design system PR in place and can use that.

[kjohnson]

@jonwaldstein this is ready for review. The design system has been incorporated and the success styles have been updated.

[jonwaldstein]

@kjohnson what was decided about the "Design Mode" and "Custom Fields" images? Looks like they are still placeholders.

[kjohnson]

@jonwaldstein I updated the screenshots.

[jonwaldstein]

@kjohnson thanks, 2 things that don't necessarily have to hold this up:

1. The "Design Mode" screenshot is an outdated form design.
2. When clicking the dismiss button it took a few seconds for me until it was removed. I don't think we necessarily need to wait for the server to respond to hide the message.

[kjohnson]

@jonwaldstein I updated the dismiss action to remove the banner async. As for the images, I'd say lets make a note for @jdghinson and move ahead with getting this PR merged.

[jonwaldstein]

@kjohnson sounds good, thanks!