Add a qualifying character to multi INSERT..VALUES parameter names

Add a qualifying character to multi INSERT..VALUES parameter names

Changed the naming convention used when generating bound parameters
for a multi-VALUES insert statement, so that the numbered parameter
names don't conflict with the anonymized parameters of a WHERE clause,
as is now common in a PostgreSQL ON CONFLICT construct.

Change-Id: I3188d100fe4d322a47d344d6a63d3e40b915f228
Fixes: #3828