added bullet.color option

[mikemeerschaert]

This pr adds the option to supply a color to the bullet object, so you can add color to the bullets without coloring the text.

I'd like to update the documentation as well, but I'm not sure how to do it, if someone can point me in the right direction I'd be happy to add that in.

e.g.

slide.addText(
  [
    {
      text: "Bullet 1",
      options: {
        bullet: { code: "25BA", color: "0000FF" },
      },
    },
    {
      text: "Bullet 2",
      options: {
        bullet: { code: "25BA", color: "FF0000" },
      },
    },

    {
      text: "Bullet 3",
      options: {
        bullet: { code: "25BA", color: "00FF00" },
      },
    },
  ]
)