[Feature Request] CTA banner themed variant

[nsolerieu]

Goal

Add a new theme prop to the CTA banner component with a set of background shapes as a additional control

See Loom walkthrough here Figma file for full specs

Specs

Background shapes

Applied to brand pillar themes

Using CSS pseudo element allow for a code only approach

• Plugs on top of existing component
• Flexes on mobile
• No performance issues
• Potential color update needed for a11y
• Extends the latest bento visual language

Extra parameters

• Disable left aligned for this expressive variant only (to avoid breaking change)
• Color theme agnostic variant would render the in light/dark modes
• Octicon should be optional toggle on/off
• Nice to have: animated reveal + onhover states

https://github.com/primer/brand/assets/10632534/863f73fb-129d-458f-8cc9-7326ed7c9de4