[C++] Timezone-aware kernels should handle offset strings (e.g. "+04:30")

[asfimport]

Both the format and the C++ library allow this, but kernels rely on a helper assuming that the timezone field of a timestamp is always a timezone name and not a timezone offset.

Reporter: David Li / @lidavidm
Assignee: Rok Mihevc / @rok
Watchers: Rok Mihevc / @rok

PRs and other links:

• GitHub Pull Request #12865

_{Note: This issue was originally created as ARROW-14477. Please see the migration documentation for further details.}

[asfimport]

Neal Richardson / @nealrichardson:
This issue has been inactive for 3 months, so it has been unassigned and marked as unstarted. If you are still working on this, feel free to reassign yourself and resume progress.

[asfimport]

Apache Arrow JIRA Bot:
This issue was last updated over 90 days ago, which may be an indication it is no longer being actively worked. To better reflect the current state, the issue is being unassigned per project policy. Please feel free to re-take assignment of the issue if it is being actively worked, or if you plan to start that work soon.

[rok]

Issue resolved by pull request 12865
#12865