Compile wikiversions.json to cdb on deploy server

Compile wikiversions.json to wikiversions.cdb in the local deploy
directory on the deployment server during scap before running additional
local content generating scripts.

This corrects a flaw in the prior logic where mw-update-l10n could
generate the ExtensionsMessages configuration file for release branch
using the source of an older branch. MWMultiVersion reads the compiled
wikiversions.cdb file rather than the wikiversions.json source file. PHP
operations that happen on the deployment host during an execution of
scap need to have access to a compiled wikiversions.cdb in the local
deploy directory (eg /usr/local/apache/common-local) that matches the
versions set in wikiversions.json from the stage directory (eg
/a/common) and the deployer's expectations.

Bug: 63659
Depends on: Ie6bb742
Change-Id: I143fc53091b96d18680e6bdecd4a832ee09856e2