feat(presets): add imagemin preset

[iuscare]

This preset compresses images (gif, png, svg, jpeg) and generates webP variants out of it. Following prop is exposed to be used in the wingsuit.config.yml

Prop	Type	Desc
webpEnabled	{Boolean | default: true}	Generate webP variants of images

Example configuration:

const namespaces = require('./source/default/namespaces');

module.exports = {
  presets: [
    '@wingsuit-designsystem/preset-tailwind2',
    '@wingsuit-designsystem/preset-postcss8',
    '@wingsuit-designsystem/preset-imagemin',
  ],
  parameters: {
    imagemin: {
      webpEnabled: false,
    },
  },
  designSystems: {
    default: {
      namespaces,
    },
  },
};

When webpEnabled is set to true, webP variants will also be generated in development mode to ensure webP can also be used within wingsuit while developing. Further optimizations of images only run in production mode. A .cache folder will be created at the root level of the application to speed up further production builds.