Migrate the preprov creds module to tempest lib

This commit migrates the preprovisioned credentials provider from
tempest/common into tempest/lib. As part of this 2 dependencies are
also migrated to lib: the InvalidTestResource exception class and the
tempest.common.fixed_network module.

Change-Id: Ib9e909aaaf81f7cb57e2382cec44598e918747b8
15 files changed