[plugin-manifest] Add option to opt-out of generating favicon (vs. pwa icon)

[madeleineostoja]

Summary

Currently gatsby-plugin-manifest automatically generates and links to a favicon as well as PWA style icons when in automatic or hybrid mode, and there's no way to opt-out of this behaviour without going full manual mode.

The plugin should expose an opt-out flag for this, as it already does for other problematic on-by-default features (eg: theme-color tags). Especially since a) favicons are arguably out of scope for a PWA manifest-style featureset anyway, and b) it's trivial for users to include their own single favicon asset.

Basic example

Easiest way to accomplish this is to add another optional config parameter to the plugin

module.exports = {
  plugins: [
    {
      resolve: `gatsby-plugin-manifest`,
      options: {
        name: `GatsbyJS`,
	...
        icon: `src/images/icon.png`,
	include_favicon: true // Defaults to true to be non-breaking
      }
    }
  ]
}

Motivation

It's very common to want very different assets for a favicon and PWA icon — eg: a small transparent icon for the favicon, and a more intricate icon with a background for the PWA manifest. While you can achieve this using 'manual' mode, that's a frustrating workaround for a fairly large use-case.

[sidharthachatterjee]

Thank you for opening this @seaneking

We would love to accept a PR adding this! Would you be interested?

[gurpreet-hanjra]

Hello, can I take this task?

[pieh]

[email protected] was released which added support for include_favicon config option.

Thanks @gurpreet-hanjra for adding support for it.