Feature: tools: show exit reason for crm_resource --force-*

While we're at it, improve the wording of the message. Don't show the numeric
execution status code, which is an internal Pacemaker detail of no interest to
users (unlike exit status codes, which are determined by the agent and could
mean something Pacemaker doesn't expect).

Example differences:

Before: Operation force-start (ocf:pacemaker:Dummy) returned: 'ok' (0)
Now: Operation force-start (ocf:pacemaker:Dummy) returned 0 (ok)

Before: Operation force-check (ocf:pacemaker:Dummy) returned: 'error' (1)
Now: Operation force-check (ocf:pacemaker:Dummy) returned 1 (error: hyperdrive quota reached)

Before: Operation force-start for test2 (ocf:pacemaker:Dummy) failed: 'Timed Out' (2)
Now: Operation force-start for test2 (ocf:pacemaker:Dummy) could not be executed

(Timed Out: Process did not exit within specified timeout)