Add support for coloring

[jcarlosroldan]

Some palette per byte range would be great, as per https://simonomi.dev/blog/color-code-your-bytes/

[theNestruo]

+1

@jcarlosroldan: not production ready yet (hardcoded colors, no settings, etc.), but take a look: https://github.com/theNestruo/vscode-hexeditor/tree/colors