Add Alert Body Prop

[jbouder]

Add new body prop to alert component, to support both existing simple text based body as well as alert components containing more advanced alert content.

Description

• Added body prop to alert to support more advanced alert body scenarios
• Added new stories and unit tests

Related Issue

N/A

Motivation and Context

• The basic alert makes use of a paragraph to display alert text. Embedding anything but text within the body results in an invalid HTML combination, resulting in a console error. This addition provides a mechanism for both existing and new body alert scenarios.

How Has This Been Tested?

• Local Testing

Screenshots (if appropriate):

[kildre]

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