Replace metalsmith-tagcleaner with a custom marked renderer

[domoscargin]

What

Replaces metalsmith-tagcleaner with a custom marked renderer which we pass to @metalsmith/in-place during conversion of our .njk files to HTML.

Why

metalsmith-tagcleaner is an unmaintained metalsmith plugin to remove <p> tags from around <img> tags. It runs after we've generated our HTML from our markdown and Nunjucks files.

In addition to a coupla NPM audit warnings, it recently started giving warnings during npm install:

npm WARN EBADENGINE Unsupported engine {
npm WARN EBADENGINE   package: 'metalsmith-tagcleaner@0.0.2',
npm WARN EBADENGINE   required: { node: '>=4.00' },
npm WARN EBADENGINE   current: { node: 'v16.14.2', npm: '8.5.0' }
npm WARN EBADENGINE }

How

We process our .njk files into HTML using @metalsmith/in-place. This relies on jstransformers under the hood, specifically jstransformer-marked, which allows us to pass in the normal marked options.

This means rather than loop over our HTML files checking the contents after they've been generated, we can instead use a custom marked renderer and avoid wrapping the images while the files are being converted. This should net us a small performance benefit.

Other notes

I've also bumped marked and both jstransformer packages. Think it makes sense to include them in this PR as they're what we're using under the hood. Changelogs are in the commit.

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[36degrees]

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