selftests/verification: Add initial RV tests

selftests/verification: Add initial RV tests

Add a series of tests to validate the RV tracefs API and basic
functionality.

* available monitors:
    Check that all monitors (from the monitors folder) appear as
    available and have a description. Works with nested monitors.

* enable/disable:
    Enable and disable all monitors and validate both the enabled file
    and the enabled_monitors. Check that enabling container monitors
    enables all nested monitors.

* reactors:
    Set all reactors and validate the setting, also for nested monitors.

* wwnr with printk:
    wwnr is broken on purpose, run it with a load and check that the
    printk reactor works. Also validate disabling reacting_on or
    monitoring_on prevents reactions.

These tests use the ftracetest suite.

Acked-by: Nam Cao <namcao@linutronix.de>
Link: https://lore.kernel.org/r/20251017115203.140080-3-gmonaco@redhat.com
Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>