Added a Database::buildStringCast and use on int/string join

Added a Database::buildStringCast and use on int/string join

The database specific sql is untested, but sql is taken from docs

mssql - knows about impilict casts -
https://technet.microsoft.com/en-us/library/ms191530(v=sql.105).aspx
mysql - knows about impilict casts
oracle - https://docs.oracle.com/javadb/10.8.3.0/ref/rrefsqlj33562.html
postgresql -
https://www.postgresql.org/docs/9.2/static/sql-expressions.html#SQL-SYNTAX-TYPE-CASTS
sqlite - http://www.sqlite.org/lang_expr.html

Bug: T69065
Change-Id: I3a83276dc65aae58124460af1810d37dff52e943