Add `pipe` format to the `arrayFormat` option

[rikjacobs1390]

Lovely package! Thanks for the great work!
However, I'd love to have the option to split multiple values with the pipe ("|") operator without being URL encoded!

For example::
/some/url?someParamGroup=10|20|30|40?someOtherParamGrou=string|some-other-string

This format is mainly used to shorten URLs which include things as identifiers, where there is expected to be a lot of them. It's a lot more readable!

Thanks in advance!

[sindresorhus]

I don't think this use-case is common enough to deserve adding yet another arrayFormat type. However, maybe you could come up with a more generic hook that would let you support your use-case and other future advanced use-cases.

[jpoehnelt]

I have this same request for pipe support. What about adding a case such as below? Could keep the 'comma' case and just fall through after setting arrayFormatSeparator = ","

arrayFormat: 'separator',
arrayFormatSeparator: "|"

Suggestions on names? I'll submit a pr.