Add banners to the flow of creating a BC from a Code Search

Created by: danielmarquespt

Add a banner on the create page if the user is creating a BC from a search result

This helps the user by bringing more context into the transition

(The copy can and should be revised)

Figma File: https://www.figma.com/file/vW0D7Os7vkQ0eFNPXhcqas/%F0%9F%A6%A1-Batch-Changes-MAIN-%5BWIP%5D?node-id=210%3A11465