[CI] Introduce assign-build:getCurrentVersionID
Summary: Extract versionID from versionInfo if it exists.
Test Plan: Got versionID as expected
Reviewers: ashoat, palys-swm
Reviewed By: ashoat
Subscribers: palys-swm, Adrian, karol-bisztyga, benschac, boristopalov
Differential Revision: https://phabricator.ashoat.com/D2369