Similar to SQL's concat and concat_ws. Should take 0, 1, 2, ... string arrays and an optional separator (default empty string) and concatenate them together, returning a string array.

For example, in the case of 2 input arrays and with the separator "-", this would take inputs:

Array<string>        Array<string>
[                    [
  "foo",               "bar",
  "push"               "pop"
]                    ]

and return output:

Array<string>
[ 
  "foo-bar",
  "push-pop"
] 

Should also accept scalar strings and recycle their values.

Reporter: Ian Cook / @ianmcook
Assignee: David Li / @lidavidm

Related issues:

• [C++] String algorithm library for StringArray/BinaryArray (is a child of)
• [C++] Add scalar string join kernel (relates to)
• [C++] String formatting kernel (is related to)
• [R][C++] Bindings for paste(), paste0(), str_c() (is depended upon by)

PRs and other links:

• GitHub Pull Request #10520

_{Note: This issue was originally created as ARROW-12709. Please see the migration documentation for further details.}