use str_getcsv instead of explode in Delimited rule

[ragulka]

Using str_getcsv to convert the delimited list into an array allows escaping commas inside the list items.

A real-life example would be list of email address specifications, ie:
"Doe, John" <johndoe@example.com>, "Doe, Jane" <janedoe@example.com>.

With the current implementation, the rule will break this into:

[
  ""Doe",
  " John" <johndoe@example.com>",
  ""Doe",
  " Jane" <janedoe@example.com>",
]

With str_getcsv, we get the expected result:

[
  "Doe, John <johndoe@example.com>",
  "Doe, Jane <janedoe@example.com>",
]

[freekmurze]

I'm a bit torn if this is a bug fix or a breaking change.

I'm going for breaking change as the validated input will be different. I would accept a PR that modifies the behaviour by calling considerCsvStrings(). When that function is called on the rule, use the str_getcsv function.

[ragulka]

@freekmurze that makes sense and I can totally see how that might break some existing use-cases. I've updated the PR with 4178cb7, although I propose a slightly shorter flag name: asCsv. What do you think?

[freekmurze]

Perfect, thanks!