Summary

I created this PR based on DantSu's #2077, which I think is a great work and highly appreciate.

This PR add basic support of reading/writing shapes and textboxes.
This can broaden the use cases of the library, for example, we can load, modify and save existing Excel files including shapes and textboxes without losing them (related issues: #1147, #2086).

To help making the PR closer to merge, compared to the DantSu's PR, I did:

• add some unit/integration tests
• add type definitions (index.d.ts)
• change the structure of some models
• resolve conflicts with the current HEAD
• add some functionalities like inner texts, line dashes and alignments

Note that some common functionalities, e.g. scRGB colors, font types and strikethrough styles, are still lacked in this PR.
I'm also willing to add a part to README document.

Test plan

ws.addShape({
  type: 'roundRect',
  rotation: 15,
  fill: { type: 'solid', color: { rgb: '4499FF' } },
  outline: { weight: 2, color: { rgb: '446699' }, dash: 'sysDash' },
  textBody: {
    vertAlign: 'ctr',
    paragraphs: [
      { alignment: 'l', runs: ["Lorem ipsum dolor sit amet, consectetur adipiscing elit."] },
      { alignment: 'r', runs: [
        { text: "Nulla eget odio sed libero ultrices vehicula.", font: { bold: true, color: { rgb: 'FF0000' } } },
      ] },
    ],
  },
}, 'B2:H8', {
  hyperlink: 'https://www.example.com',
  tooltip: 'Example Link',
});

Related to source code (for typings update)