This patch locks down search_path in extension install and update
scripts to only contain pg_catalog, this requires that any reference
in those scripts is fully qualified. Additionally we add explicit
create commands to all update scripts for objects added to the
public schema. This change will make update scripts fail if a
function with identical signature already exists when installing
or upgrading instead reusing the existing object.
This patch splits the timescaledb_fdw sql file into two parts to
separate the idempotent parts from the non-idempotent ones so
the function definitions can be included in the regular update
script.
