VM accessors take VM as implicit argument, not explicit argument

VM accessors take VM as implicit argument, not explicit argument

* libguile/vm.h:
* libguile/vm.c:
  (scm_vm_apply_hook, scm_vm_push_continuation_hook,
  scm_vm_pop_continuation_hook, scm_vm_abort_continuation_hook,
  scm_vm_restore_continuation_hook, scm_vm_next_hook,
  scm_vm_trace_level, scm_set_vm_trace_level_x, scm_vm_engine,
  scm_set_vm_engine_x, scm_c_set_vm_engine_x): The VM argument is now
  implicit: the VM for the current thread.

* doc/ref/api-debug.texi (VM Hooks): Try to adapt.

* module/ice-9/command-line.scm:
* module/statprof.scm:
* module/system/vm/coverage.scm:
* module/system/vm/trace.scm:
* module/system/vm/trap-state.scm:
* module/system/vm/traps.scm:
* test-suite/tests/control.test:
* test-suite/tests/eval.test: Adapt users that set hooks or ensure that
  we have a debug engine.