[R] Support dplyr verb transmute()

[asfimport]

Add support for the dplyr verb transmute()

Reporter: Ian Cook / @ianmcook
Assignee: Neal Richardson / @nealrichardson

Related issues:

• [R] Support dplyr::mutate() (is fixed by)
• [R] Updates for compatibility with dplyr 1.0 (relates to)

_{Note: This issue was originally created as ARROW-11284. Please see the migration documentation for further details.}