Fixes Typography bug with invalid HTML tags in `as` prop

[Mil4n0r]

Checklist

• [x] Build process is done without errors. All tests pass in the /lib directory.
• [x] Self-reviewed the code before submitting.
• [x] Meets accessibility standards.
• [x] Added/updated documentation to /website as needed.
• [x] Added/updated tests as needed.

Description Modified BaseTypography component to prevent unexpected tags to be assigned to the as prop

Additional context Some basic unit testing was also added in order to ensure that invalid tags are replaced with "span".

"a" | "blockquote" | "cite" | "code" | "div" | "em" | "figcaption" | "h1" | "h2" | "h3" | "h4" | "h5" | "h6" | "p" | "pre" | "small" | "span" | "strong"

Discussion: #1842

Closes #1621

[Mil4n0r]

This is closed for now as it requires some discussion regarding what subset of tags is considered valid.

[Mil4n0r]

Reopened.