tests: update template and add pids

Generalised the library API tests and created a common
test-runner. Instead of copy and pasting the same code in
each time.

First cut of pids API test, for _new so far.

proc/.gitignore

@@ -1,4 +1,5 @@
 test_namespace
+test_pids
 test_sysinfo
 test_uptime
 test_version