Leverage config colors via `ConsoleCodes.wrap`.

Support for this was added recently in #1531.
Remove unneeded base class helper methods.
`summary_line` -> `results_line`; `colorized` -> `colorized_results_line`.

The summary is more than the one line. The specific
line returned by the method is the result summary so
this is a better name.

`colorized` is too generic of a name, given the object
exposes multiple colorized things.
No need for long/short padding methods.
Expose fully formatted helper methods off of the notifications.

This is useful for 3rd party formatters that want to format
some things the same as we do.
Remove unneeded base class method.
Add changelog entry.

[ci skip]
Rename `results_line` to `totals_line`.

This seems to be the closest thing to a consensus we’re going
to get.
Merge pull request #1533 from rspec/myron-formatter-refactoring

Further formatter refactoring