Inline Alert: loosen constraints on description slot

Bookmarking for investigation as an enhancement to Inline Alert:

> This is just feedback on the `InlineAlert` itself, but it would be nicer IMO if we had done InlineAlert's `description` so it was just a slot for any old content instead of a text string. These use cases where we're the using the button slots for documentation links that could be inline make me go "ah yeah we just need colorful divs" for the vast majority of use cases, like CMS Lite.

_Originally posted by @ty2k in https://github.com/bcgov/design-system/pull/611#discussion_r2691705178_

Start with the InlineAlert component and the discussion in pull request #611 linked from the issue. Confirm how the description currently accepts content and identify the existing tests or examples covering it; done means the description supports arbitrary inline content while preserving existing text usage.

Written by the indexing model from the issue text.