Same implementation as pinojs#493 but using object for extras argument for compatibility with future signature expansion

Enables users to use available colors based on `colorize` context of the pino-pretty instance

Variant of pinojs#494 that provides colors as extras object for compatibility with future customPrettifier extras argument

All keys for customPrettifier, other than logs, now provide colors as property on an additional `extras` object for the prettifyObject function signature

# Conflicts:
#	index.d.ts

* Modify level prettifier function signature to match other prettifiers
  * Since only the first argument was documented anyway this shouldn't be a breaking change.

…unction signature