Add tests for "Transfer" section in CommonsHelperConfigParser
Including a bunch of minor edge-cases.
The trim() in WikiTextConversions is a quick workaround just to get this
here done, independently from the other patch. But this is already better
fixed in an other patch. The order in which these are merged does not
matter. One needs a rebase then.
Bug: T194505
Change-Id: Idffbc33a484f857a0c6d7c55a6dbeee2c8a4e54f