Enhancement: support line breaks in Response for Multiple Choice Checkbox

### Impacted plugin

Jetpack

### What

The spacing in the form response should include line breaks for each checkbox item.

### How

When a new form is created, multiple choice items appear on separate lines in the form (both front and backend), however when the form submissions are viewed, either in the feedback area of wp-admin, or in the email that is sent, the items appear all on the same line, with commas separating them, making the results more difficult to read.

Example of form:


Example of results in the feedback section (and similar display in automated emails that are sent):


### Requested results

Display checkbox items on separate lines in feedback and email results.

Closest related open issue found: https://github.com/Automattic/jetpack/issues/41428

Start by reproducing a Jetpack multiple-choice checkbox submission and compare its display in the wp-admin feedback area with the automated email result. Trace the response formatting used by both views; done means each checkbox item appears on its own line in feedback and email results.

Written by the indexing model from the issue text.