Use IRB's coloring helper to colorize source

[st0012]

Since IRB already has coloring helpers, I figure it'd better to use it instead of having this library's own one? If this is a reasonable approach, I can use the same helper to colorize the backtrace in another PR. Some notes:

1. Because this library will be Ruby 3.1's default, the irb should always have the coloring feature (added after 2.7).
2. I assume that if the debugger can start, the frame's source file must be "complete". So I choose the default complete mode.

Result:

[ko1]

Thanks.

• The source should be cached. I'll fix it.
• This should be configurable. I'll fix it.
• There is NO_COLOR rule https://no-color.org/ but not sure we support it. At least, I'm discussing irb devs.

[ko1]

irb's coloring doesn't support crlf line break. I'll fix it too.

[st0012]

The source should be cached

yeah I think we can store the colorized lines inside the frame. is that what you're thinking too? if that sounds good I can implement it. (#28)

This should be configurable

Will adding the --nocolorize flag (like irb) and RUBY_DEBUG_NOCOLORIZE env work?

irb's coloring doesn't support crlf line break.

ah sorry I didn't even notice that it'd be a problem 😕

[ko1]

Not sure --nocolorize is the best (--no-xxx is another manner).
Not so important, so wait to add it.