thermal: intel: selftests: workload_hint: Support slow workload hints

thermal: intel: selftests: workload_hint: Support slow workload hints

Add option to enable slow workload type hints. User can specify
"slow" as the command line argument to enable slow workload type hints.
There are two slow workload type hints: "power" and "performance".

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://patch.msgid.link/20251218222559.4110027-3-srinivas.pandruvada@linux.intel.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>