feat(js-toolkit): adds support for building theme spritemap client extensions

[bryceosterhaus]

Config for this CET looks like

{
    "build": {
        "type": "themeSpritemap",
        "options": {
            "extendClay": true
        }
    }
}

Icons are placed in the ./src of your project.

package.json looks like

{
  "name": "sample-theme-spritemap-3",
  "version": "1.0.0",
  "description": "Sample Theme Spritemap 3",
  "dependencies": {
    "@liferay/dxp-7.4": "*"
  },
  "scripts": {
    "build": "liferay build",
    "clean": "liferay clean",
    "deploy": "liferay deploy"
  }
}

[bryceosterhaus]

@izaera updated

and yeah I still need to figure out the test failures

[izaera]

LVGTM :+1: