[Next.js][Editing] Partial rendering implementation

[illiakovalenko]

Description / Motivation

We need to support rendering of a single component for editing purposes. This will be used by Pages (no plans for EE to use). It utilizes the same /api/editing/render endpoint and middleware

Testing Details

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)