Allow for custom cache keys for Importmap::Map#preloaded_module_paths and Importmap::Map#to_json

[dhh]

If you're using a custom asset host resolver, you may need to use separate caches for the preloaded module paths and json returns. Otherwise the first resolved asset host will be used to generate these values, which as then cached for all subsequent requests.

We use this in HEY as a consequence of the following asset host resolver:

  # Disable the CDN only for the iOS app to allow the app's local proxy to intercept network requests for assets
  config.action_controller.asset_host = Proc.new do |source, request|
    unless request&.user_agent.to_s.match?(/HEY iOS/) && source =~ /\.(css|js)$/
      "https://production.haystack-assets.com"
    end
  end

That allows us to call javascript_inline_importmap_tag like so:

javascript_inline_importmap_tag(Rails.application.importmap.to_json(
  resolver: self, cache_key: "#{platform.ios_app? ? "ios_app" : "all"}_json"
))

[packagethief]

Driving by with a heads-up: custom cache keys won't be cleared by Importmap::Map#clear_cache.

[dhh]

Good catch. Will fix that.

[dhh]

Fixed in 459f108