Consolidate InsightTemplatesBanner & SearchTemplatesBanner

Created by: BolajiOlajide

We currently have two banners with the following description:

• SearchTemplatesBanner: shown when a user creates a batch change from Search
• InsightTemplatesBanner: shown when a user creates a batch change from a code insight

These banners share a lot of similarities - it makes sense to create a base component that contains the shared visual styles and banners can make use of such component.