Consider utils for colored strings

[pskfyi]

The Deno standard library provides color functions, which wrap strings in ANSI color codes, resulting in the strings appearing as various colors in the console. This has some rough edges, in particular around string length which is augmented by the color codes but not visible, making it easy to become confused and introduce errors.

We should consider something like a FormattedString class which wraps the desired abilities, but could expose common string properties like length with respect to the original input string. This would be useful in evalCodeBlocks and upcoming Cursor functions, but could also widely be used in Deno.customInspect functions to customize console log output for all scripts or classes.