Add the sign function to the compute kernels.

sign(X) =

• 1 if X > 0
• 0 if X = 0
• -1 if X < 0

Reporter: Eduardo Ponce / @edponce
Assignee: Eduardo Ponce / @edponce

Related issues:

• [C++] Arithmetic kernels for numeric arrays (is a child of)
• [C++][Compute] Add explicit output values to sign function and fix unary type checks (incorporates)
• [R] Bindings for sign() (is depended upon by)

PRs and other links:

• GitHub Pull Request #10395

_{Note: This issue was originally created as ARROW-12861. Please see the migration documentation for further details.}