tests/drv_hangman: Convert test from shell script to c

tests/drv_hangman: Convert test from shell script to c

Mixing script and standlone tests didn't mix well with the
strict i915_ring_stop flags handling. Also squash drv_missed_irq_hang
to the new test.

v2: - Remove missed irq test (Daniel Vetter)
    - gitignore fixed (Oscar Mateo)
    - fix check_other_clients to handle dangling fd's

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=78322
Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Oscar Mateo <oscar.mateo@intel.com> <v1>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>