feat(svelte5): incorporate Svelte 5 support into main entry point

[mcous]

Overview

Given that Svelte 5 has reached RC status, this PR incorporates Svelte 5 support back into the main index.js export while continuing to support Svelte 3 and 4.

Changes

This PR takes @yanick's SvelteTestingLibrary and Svelte5TestingLibrary idea, but switches the behavior modification from from a "is a" dependency model to a "has a" dependency model.

For our library's needs, the differences between Svelte 4 and 5 are small:

• "render" - Call mount(Component) instead of new Component()
• "cleanup" - Call unmount(component) instead of component.$destroy
• "update props" - Use a $state signal for props instead of component.$set

svelte-testing-library layers on testing-library and public API niceties, which are common to all Svelte versions. Rather than including both the public API layer and the underlying render implementation in a pair of classes, the public API has been reworked back into set of exported functions. Those functions now have access to methods from a core module that provides a facade over the Svelte render differences listed above.

Status

• Working with Vitest
• Blocked Working in Jest - Call compileModule for .svelte.js files in Svelte 5 svelteness/svelte-jester#282

[github-actions]

🎉 This PR is included in version 5.2.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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