Use environment variables for configuration in developer tooling

Avoid the need for configuration files for temporary database connections.

test/create_test_db

@@ -68,4 +68,9 @@ PGDATABASE=$DB PGOPTIONS='-c client_min_messages=WARNING' psql "$URI" --set=db=$
 EOF
 
 # Create a new connection string to use with the test runner
-echo 'postgres://'${TEST_USER_NAME}':'$TEST_USER_PASS'@'$HOST_PORT'/'$DB
+export PGRST_DB_URI="postgres://${TEST_USER_NAME}:$TEST_USER_PASS@$HOST_PORT/$DB"
+export PGRST_DB_ANON_ROLE="postgrest_test_anonymous"
+export PGRST_DB_SCHEMAS="test"
+
+shift 2
+"$@"