Add CICP color metadata and PNG support

[VentuzTammoHinrichs]

Prerequisites

• [x] I have written a descriptive pull-request title
• [x] I have verified that there are no overlapping pull-requests open
• [x] I have verified that I am following the existing coding patterns and practice as demonstrated in the repository. These follow strict Stylecop rules :cop:.
• [x] I have provided test coverage for my change (where applicable)

Description

This PR adds a SixLabors.ImageSharp.Metadata.Profiles.Cicp.CicpProfile class containing a CICP color profile (as per ITU H.273) to the image and frame metadata, and also PNG support for the new cICP chunk.

[CLAassistant]

All committers have signed the CLA.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}