Feature/4691 cta block

[kevinhowbrook]

Description

⚠️ based on #11550 with picks from #11527 (because it's behind)

This adds a new CTA block type, it looks like this

Link to sample test page:
Related PRs/issues: https://torchbox.monday.com/boards/1334760528/pulses/1336814691

Checklist

Tests

• Is the code I'm adding covered by tests?

Changes in Models:

• Did I update or add new fake data?
• Did I squash my migration?
• Are my changes backward-compatible. If not, did I schedule a deploy with the rest of the team?

Documentation:

• Is my code documented?
• Did I update the READMEs or wagtail documentation?

Merge Method
💡❗Remember to use squash merge when merging non-feature branches into main