chore: upgrade to latest Prismic package standards

[angeloashmore]

Types of changes

• Chore (a non-breaking change which is related to package maintenance)
• Bug fix (a non-breaking change which fixes an issue)
• New feature (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Description

This PR upgrades the repository's infrastructure to the latest Prismic OSS standards.

It includes the following changes:

• Replace AVA with Vitest
• Replace Istanbul with c8
• Add Size Limit

Checklist:

• My change requires an update to the official documentation.
• All TSDoc comments are up-to-date and new ones have been added where necessary.
• All new and existing tests are passing.