Add a Blueprint for WP.org Live Preview

[brandonpayton]

Hi there, this PR proposes to add a Blueprint file so that Better Search Replace can have a Live Preview button in the WP.org plugin repo. The Live Preview will load your plugin in the WordPress Playground web app using the provided Blueprint.

According to the WP.org docs:

There are two things required for a plugin preview button to appear to all users:

1. A valid blueprint.json file must be provided in a blueprints sub-directory of the plugin’s assets folder.
2. The plugin preview must be set to “public” from the plugin’s Advanced view by a committer.

Once those conditions are met, a Live Preview button should appear next to the Download button in the WordPress.org plugin repo, like:

Try this link for an example of the preview. Note: This link's hash component is just the Base64-encoded JSON of the Blueprint, and you can decode in your browser's dev tools console with JSON.parse(atob(<hash-value>)).

Would this PR be useful to you?

[brandonpayton]

It looks like I was mistaken about where to place the blueprint.json file. I believe it belongs under the top-level assets directory for the plugin, under assets/blueprints and not under trunk/assets/blueprints.

Perhaps this should have been an issue with an example blueprint.json instead of a PR.