Allow user to request globally unique ids

[chris48s]

Discussed in #10321

The IDs on the linearGradient and clipPath SVG elements are the same for every badge. This means the IDs are unique within any given SVG document, but if you embed multiple SVGs inline in a single HTML document then the IDs aren't unique within the HTML page.

This leads to this behaviour:

This is a fairly uncommon use-case and for shields.io itself it is useful that the IDs are single character. However, it would be useful for the makeBadge() function to expose a non-default option which allows the user to specify they want globally unique IDs.

We could do this without adding any additional dependency by using crypto.randomUUID() from the node standard library to generate the IDs:

const { randomUUID } = require('crypto');
console.log(randomUUID());