USWDS - Validation: Add screen reader summary on init

[amyleadem]

Summary

Added a screen reader summary of input requirements to the validation component on initialization. Previously, the component only provided this summary when the user added content to the input.

Breaking change

This is not a breaking change.

Related issue

Closes #5841

Related pull requests

Changelog PR

Preview link

Validation component

Problem statement

If a screen reader user navigates via the tab key, they will arrive on the validation component input without being made aware of the validation requirements.

Solution

Ran the validate() function on init. Previously, the function was designed to be called only on update. This required the following changes:

1. Removed the debounce from the validate() function. This debounce should only be added on update.
2. Added the validate function to init
3. Added debounce to handleChange()

Testing and review

1. Confirm that the status summary appears in the #code-sr-summary element on component initialization
2. Confirm that the status summary appears in the #code-sr-summary element when you update the input
3. Confirm that code meets standards