feat(hits): add banner to instantsearch-js hits widget

[taylorcjohnson]

Summary

This is the third pull request to add support for no-code banners to the Hits widget (RFC). Building on the recent changes to the Hits instantsearch-ui-component it updates the Hits instantsearch-js widget to support a new banner template.

EMERCH-1421

There will be a follow-on PR to update React InstantSearch.

Result

The hits widget tests have been updated to ensure that the new class names (bannerRoot, bannerImage, and bannerLink) and new optional banner template (using the html template string and JSX approaches) are supported. No styling was applied in the examples or to instantsearch.css - that will most likely come in a follow-up PR.

Additionally, the code was tested in the getting-started example codebase (connected to appId: F4T6CUV2AH, index: products in the beta environment - where the test rules with a banner consequence exists).

Getting Started App (no query, with updated item template to match new index):

Getting Started App (query: nikon; nikon camera promotion alt text and links to https://www.nikonusa.com/):

Getting Started App (query: doesnotexist; to demonstrate banner without hits):

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Latest deployment of this branch, based on commit 99e82f6:

Sandbox	Source
example-instantsearch-getting-started	Configuration
example-react-instantsearch-getting-started	Configuration
example-react-instantsearch-next-app-dir-example	Configuration
example-react-instantsearch-next-routing-example	Configuration
example-vue-instantsearch-getting-started	Configuration