[Python][CI] Create a build for validating python docstrings

[asfimport]

Reporter: Krisztian Szucs / @kszucs
Assignee: Krisztian Szucs / @kszucs

Related issues:

• [Python][Doc] Exercise numpydoc in the CI checks (supercedes)

PRs and other links:

• GitHub Pull Request #7732

_{Note: This issue was originally created as ARROW-13208. Please see the migration documentation for further details.}

[asfimport]

Krisztian Szucs / @kszucs:
Issue resolved by pull request 7732
#7732