Add hyperlinks

[bluehaoran]

What?

Adds PDFPage.drawLink() so users can add hyperlinks easily.

Why?

I personally needed to add several hyperlinks to a PDF. I added createPageLinkAnnotation per the suggestion in #555, got it working in our project, and then generalised it for broader use.

See also: #555, #691 , #980

How?

This follows @Hopding 's suggestion in #555.

I dug into the PDF Specification to double-check the possible setting for Border and Colour.

I have not provided all possible options; I wanted something simple and working before adding extra options.

Testing?

Added basic Unit test in PDFPage.spec.ts.

New Dependencies?

No.

Screenshots

Suggested Reading?

Yes, read the PDF Spec.

Anything Else?

Nope.

Checklist

• I read CONTRIBUTING.md.
• I read MAINTAINERSHIP.md#pull-requests.
• I added/updated unit tests for my changes.
• [] I added/updated integration tests for my changes.
• [] I ran the integration tests.
• I tested my changes in Node, Deno, and the browser.
• I viewed documents produced with my changes in Adobe Acrobat, Foxit Reader, Firefox, and Chrome.
• I added/updated doc comments for any new/modified public APIs.
• My changes work for both new and existing PDF files.
• I ran the linter on my changes.

[bluehaoran]

PS: the CircleCI build seems to be broken.