Report Widgets Core: Add support for content sections Level 3

Context

This is part of the epic: &6647 (closed) that adds support for the Design Guidelines to the Core component of MR Report Widgets.

All this is in the context of the Working Group: Merge Request Report Widgets.

Required reading

Please ensure that:

• all the code written implements the rules of Accessibility https://design.gitlab.com/regions/merge-request-reports#accessibility
• you're familiar with the overall goal https://www.figma.com/file/qEddyqCrI7kPSBjGmwkZzQ/Component-library?node-id=38193%3A30482

Task

Implement the content sections for Level 3:

• Status
• Subject
  • Section title and description
  • Text
  • Meta

• Section title and description - groups level 2 and level 3 status items. A description must be preceded by a title, but a title does not require a description.
• Text - identifies the item, what it means for a user, and how to remedy problems. It can contain inline links and formatting to emphasize text.
• Meta - supplemental text, links, and badges that add meaningful context to an item. Text can include formatting for emphasis.

See https://design.gitlab.com/regions/merge-request-reports#content-sections