Change default configuration of prefer-d

[RunDevelopment]

I just added eslint-plugin-regexp to a code base with some regexes and the prefer-d rule wanted to replace all character classes like this [0-9a-f] with this [\da-f]. While I think that prefer-d has a place in our recommended config, but I think it's too aggressive by default. [0-9a-f] -> [\da-f] is a minor stylistic change to enforce consistency, but it will increase the diff for existing code bases and it won't improve the readability. Since 0-9 is relatively common from what I've seen, prefer-d currently causes a lot of noise for little gain.

So I think it might be a good idea to change the default configuration of prefer-d from insideCharacterClass: "d" to insideCharacterClass: "ignore". This would still transform [0-9] -> \d but it will leave [0-9a-f] and [\da-f] as is.

With this change, prefer-d will report strictly fewer errors, so this is a minor change according to ESLint's semver policy.

What do you think @ota-meshi?

[ota-meshi]

Sounds good to me!

With this change, prefer-d will report strictly fewer errors, so this is a minor change according to ESLint's semver policy.

Yeah, I think we can do it in a minor version 👍