generator: Group and move APIs from actions.ml into actions_*.ml.

Group the APIs logically and move them into new modules:

Actions_core:
  Core APIs and anything that doesn't fit into another group, eg. launch.
  (With some more effort this could be split further.)

Actions_augeas:
  Augeas APIs, eg. aug-init.

Actions_debug:
  Debug APIs.

Actions_hivex:
  Hivex APIs, eg. hivex-open.

Actions_inspection:
  Inspection APIs, eg. inspect-get-type.

Actions_properties:
  Handle properties, eg. set-hv, get-hv.

Actions_tsk:
  SleuthKit APIs, eg. filesystem-walk.

*_deprecated:
  All of the above modules have deprecated variants, where we
  place the deprecated actions.

docs/guestfs-hacking.pod

@@ -349,7 +349,7 @@ To add a new API action there are two changes:
 =item 1.
 
 You need to add a description of the call (name, parameters, return
-type, tests, documentation) to F<generator/actions.ml>.
+type, tests, documentation) to F<generator/actions_*.ml>.
 
 There are two sorts of API action, depending on whether the call goes
 through to the daemon in the appliance, or is serviced entirely by the
@@ -395,12 +395,12 @@ the OCaml description.
 
 You can supply zero or as many tests as you want per API call.  The
 tests can either be added as part of the API description
-(F<generator/actions.ml>), or in some rarer cases you may want to drop
+(F<generator/actions_*.ml>), or in some rarer cases you may want to drop
 a script into C<tests/*/>.  Note that adding a script to C<tests/*/>
 is slower, so if possible use the first method.
 
 The following describes the test environment used when you add an API
-test in F<actions.ml>.
+test in F<actions_*.ml>.
 
 The test environment has 4 block devices: