Decouple Doc data structure from Ansi console

[pwentz]

• Remove use of Formatter type alias from Color, Underline, and Bold constructors in favor of applying the formatting to the content during the rendering process (display). This allows the Doc and ` data structure itself to remain uncoupled from the ANSI console.
• Color type constructors now have a ColorBrightness sum type (Standard | Dark).
• RestoreFormat and best now take isBold and isUnderline bool types over Maybe Formatter types.
• WithFormat and WithBold (TextFormat) no longer take Formatter arg.
• Fn's from Console moved to consoleFormatting and toAnsiColor, and ansiBrightness functions.
• ConsoleLayer -> DocLayer
• Remove Formatter type alias