Add carriage return "\r" to showInvisibles

[BPScott]

Prettier will format files using the first line-ending it sees. This means that files that use
\r\n as line breaks will keep them.

showInvisibles has conversions for space, \n and \t. It'd be good if it had a replacement for \r as well so report output doesn't look goofy for crlf files as the terminal tries to render the literal carriage return.

Unfortunately I'm not sure what the best solution for this is. There's no character that screams "I'm a carriage return" that I'm aware of. Perhaps ⏎ can be used for \n (as it is now), and a slightly different character can be used for a \r\n combo?

I reckon we can ignore files with just \r line endings (macos 9 lols)

[not-an-aardvark]

I suppose another option would be to use ⏎ for both \r\n and \n, although maybe that would end up confusing because we would end up with messages like "Replace ⏎ with ⏎ ".

Another option would be to use the literal text \r (backslash followed by r) for carriage returns.

[BPScott]

"Replace ⏎ with ⏎ " is a confusing and I'd like to avoid it. Literal \r feels odd as it doesn't currently use escape codes for other characters.

How about ␍ (see https://en.wiktionary.org/wiki/%E2%90%8D)

[not-an-aardvark]

Sounds good to me. Would you be interested in creating a PR?

[BPScott]

There you go ^^