This functions returns a data table of key-value pairs for the
database settings, which are parsed from the respective config tab
from the shiny application.
Arguments
input
Shiny server input object.
target
A boolean (default: TRUE).
db_type
(String) "postgres" or "oracle".
displayname_gui
(String) "i2b2 (Prod)"
rv
The global 'reactiveValues()' object, defined in server.R