Removed custom agent wait-for install-complete code.
Moved installer WaitForInstallComplete function from
cmd/openshift-install/main to cmd/openshift-install/command so
that the function can be made public.
Modified agent.newWaitForInstallCompleted() to use the common
WaitForInstallComplete function.
The benefit of moving agent over to the common
WaitForInstallComplete function is that the common function has a
step to wait for operators to be in a stable state before calling
the cluster installation complete.
Updated "agent wait-for" commands to also call
SetupFileHook(RootOpts.Dir) so that it logs to the common
.openshift_install.log file.
Moved log.go and rootOpts to a command package so that it can
be shared with agent wait-for.
