Ability to control carousel count

### User Story

As an author, I want the ability to limit the number of products displayed in the `Related Products`.

### Description & Motivation

Instead of showing all the products available, I would like to showcase a limited number of products in the Related Products component to entice customers to click into another page.

### Deliverables

Provide a way for content authors to provide a limit to the number of products displayed. If provided, the component should display at most that many products in the component. This would require code change.

### Acceptance Criteria

Should have the ability to author a maximum number of products to showcase.
Should be able to "revert" back to default behavior.
When authored, the component should render up to the authored maximum limit.

### Verification Steps

Author the component and verify the default (existing) behavior works as expected.
Configure the component to have a limit on the number of products displayed.
Verify that no more than the authored limit show up.
Configure the component to revert back to the default behavior.
Verify that all products show up.

Start by locating the Related Products component and its authoring configuration in the repository. Check how the component currently determines the products it renders, then verify the existing default behavior, an authored maximum, and reverting to the default as described in the verification steps.

Written by the indexing model from the issue text.