Remove the _alerts.scss stylesheet

[jamigibbs]

Description

With the va-alert web component available, we should now be able to replace any usages of the old alert style classes and remove the old stylesheets:

• /stylesheets/formation-overrides/components/_alerts.scss
• /stylesheets/modules/m-alert.scss

In some situations if an old alert class is just being used in a single application, it might make sense to move that style directly into vets-website.

Tasks

• Search vets-website, content-build, and next-build for any usages of the old alert classes
• If there are any left, replace them with va-alert web component
• Remove the unused stylesheets from CSS-Library
• Remove any related assets from the CSS-Library:
  - success.png
  - success.svg
  - warning.png
  - warning.svg
  - error.png
  - error.svg
  - info.png
  - info.svg

Acceptance Criteria

• All places where the old alert classes are being used have been replaced with va-alert
• Unused alert styles and assets have been removed from the CSS-Library