add display attribute to hyperlinks

[phaseOne]

Issue

This resolves an import issue with Google Sheets where the cell's text content is lost. On import, Sheets converts hyperlinks to a HYPERLINK formula. When the <hyperlink> lacks a display attribute, it drops the text content of the cell and replaces it with the location of the hyperlink.

Example

An XLSX with the following <hyperlink>:

<hyperlink ref="E2" location="'Sheet1'!A3"/>

When imported into Google Sheets, E2 becomes:

=HYPERLINK("#gid=1368866318&range=A3","#gid=1368866318&range=A3")

Change

This change automatically sets the display attribute of a <hyperlink> based on the cell's value.

I don't see much of a reason to expose the display attribute in the API like the Tooltip property, since it "should" always be the cell's value.

I've only made this change to the XLSX format renderer. Contributions for XLSB and other formats, tests, and feedback on my implementation are welcome.

Quirks Observed

1. When opening an XLSX in Excel generated by this package (before this PR), Excel natively sets the display attribute of all <hyperlink>s on save, even if they previously did not have this attribute.

2. Excel will render the underlying text content of the cell and ignores the display attribute of the <hyperlink>, even if they differ. Google Sheets clobbers the text content and only uses the display attribute to set the HYPERLINK formula's link label.

[SheetJSDev]

Google Sheets does not currently import XLSB but does import XLS (so we'd need to check that behavior, but that can happen in a different issue/PR)

External links seem to work without the attribute in Google Sheets (you can try the examples on https://docs.sheetjs.com/docs/csf/features/hyperlinks) but we can reproduce the issue with internal links.

Did you test if the patch works with same-sheet links (e.g. ws["C1"].l = { Target: "#E2" };)

[SheetJSDev]

Testing today (2022-09-23):

• External links to sites work without display
• mailto links work without display
• Local links are lost (irrespective of display setting)
• Internal single-cell / range / name / scoped references are rewritten without display