Move from use of sanitize for CSS normalisation to "modern CSS reset"

[Antranig Basman]

Following discussion in the Fluid Design Matrix chat at https://matrix.to/#/!CiNvDHGGdtIVCpYoGy:matrix.org/$3grOKZ9M5aKm49orKwJwD5STiOaIcAN0Jb2E5ssoPrs?via=matrix.org it was determined we should move from the historical choice of sanitize.css to a more minimal library - initially prompted by the "opinionated" CSS rule that overrides the browser's default choice of cursor which may be confusing for some users.

The original evaluation for a normalisation library was done at #108 but the rationale for choosing sanitize.css was not recorded.

@greatislander reported that many of our projects are moving away from more heavyweight CSS normalisation, and in particular Infusion itself moved away from normalise.css in https://issues.fluidproject.org/browse/FLUID-6607. He suggested the use of a more minimal, modern library such as https://piccalil.li/blog/a-modern-css-reset/ (in npm as https://www.npmjs.com/package/modern-css-reset ) as a good alternative.