tree-wide: extend verbs functions with extra per-verb data parameter

We often have a pattern where the same verb function is used for
multiple actions. This leads to an antipattern where we figure out what
action needs to be taken from argv[0] multiple times: often once in
parse_argv() to figure out what options are allowed, then once again
implicitly in dispatch_verb(), and then again in the action verb itself.
Let's allow passing a parameter into the verb to simplify this.

This matches a pattern we have in conf-parser.h, where we have both
void *userdata (more global) and void *data (per-config item). Here,
I opted for uintptr_t userdata. It seems that most of the time we'll
want to just pass an enum value. This works OK with no casts. I also
tried a void* and union. In both cases, much more boilerplate is needed:
either a cast or a macro to help avoid compiler warnings. uintptr_t
seems generic enough to cover foreseeable usecases with no fuss.

This is a noop refactoring. See next commit for an example.

src/systemctl/systemctl-reset-failed.c

@@ -10,13 +10,13 @@
 #include "systemctl-trivial-method.h"
 #include "systemctl-util.h"
 
-int verb_reset_failed(int argc, char *argv[], void *userdata) {
+int verb_reset_failed(int argc, char *argv[], uintptr_t data, void *userdata) {
         _cleanup_strv_free_ char **names = NULL;
         sd_bus *bus;
         int r, q;
 
         if (argc <= 1) /* Shortcut to trivial_method() if no argument is given */
-                return verb_trivial_method(argc, argv, userdata);
+                return verb_trivial_method(argc, argv, data, userdata);
 
         r = acquire_bus(BUS_MANAGER, &bus);
         if (r < 0)