Introduces [console]port_range configuration option and implements
the feature of automatic port allocation for IPMI based serial console.
The ipmi_terminal_port in driver_info takes precedance if specified,
otherwise ironic will allocate free port from configured port range
for underlying serial proxy tools.
The implementation deviation with the original proposal is this patch
doesn't validate whether user specified ipmi_terminal_port falls in the
range, based on following considerations:
a. ipmi_terminal_port is considered a resort for backwards compatibility,
we will remove this eventually.
b. different conductors may have different port range configured (rare,
but could happen).
c. force ipmi_terminal_port in the port range could raise the
possibility of conflicts with ports in the configured range, this is not
a desired result, so leave the choice to the end users.
Change-Id: If8722d09dc74878f4da2e4a7f059d9b079c3e472
Story: 2007099
Task: 38135
b3721ce4ff