Configuration:
- PDF.js version: 2.0.550

Steps to reproduce the problem:
1. Render document in SVG mode `renderMode="svg"`

What is the expected behavior? (add screenshot)
Rendering annotations same way as they rendered on canvas

What went wrong? (add screenshot)
```
Warning: Unimplemented operator beginAnnotations
Warning: Unimplemented operator endAnnotations
```
"123 0 obj\n" +
          "<< /Type /Annot /Subtype /Widget /FT /Tx /DA (/Goth 5 Tf) /DR " +
          "<< /Font << /Helv 314 0 R /Goth 159 0 R>>>> /Rect [0 0 32 10] " +
          `/V (\xfe\xff${utf16String}) /AP << /N 2 0 R>> /M (date)>>\nendobj\n`
      
      expect(newData.data).toEqual(
        "2 0 obj\n<< /Length 82 /Subtype /Form /Resources " +
          "<< /Font << /Helv 314 0 R /Goth 159 0 R>>>> /BBox [0 0 32 10]>> stream\n" +
          `/Tx BMC q BT /Goth 5 Tf 1 0 0 1 0 0 Tm 2.00 2.00 Td (${utf16String}) Tj ` +
          "ET Q EMC\nendstream\nendobj\n"
      
    }
  }
  describe("ButtonWidgetAnnotation", function () {
    let buttonWidgetDict;
    beforeEach(function () {
      buttonWidgetDict = new Dict(
      buttonWidgetDict.set("Type", Name.get("Annot")
      buttonWidgetDict.set("Subtype", Name.get("Widget")
      buttonWidgetDict.set("FT", Name.get("Btn")
    }
    afterEach(function () {
      buttonWidgetDict = null;
    }
    it("should handle checkboxes with export value", async function () {
      buttonWidgetDict.set("V", Name.get("1")
      buttonWidgetDict.set("DV", Name.get("2")
      const appearanceStatesDict = new Dict(
      const normalAppearanceDict = new Dict(
      normalAppearanceDict.set("Off", 0