qom: Implement qom-set HMP command

Re-implemented based on qmp_qom_set() to facilitate argument parsing.

Warn about ambiguous path arguments.

Reviewed-by: Gonglei <arei.gonglei@huawei.com>
Tested-by: Alistair Francis <alistair.francis@xilinx.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>

hmp-commands.hx

@@ -1684,6 +1684,19 @@ ETEXI
 STEXI
 @item qom-list [@var{path}]
 Print QOM properties of object at location @var{path}
+ETEXI
+
+    {
+        .name       = "qom-set",
+        .args_type  = "path:s,property:s,value:s",
+        .params     = "path property value",
+        .help       = "set QOM property",
+        .mhandler.cmd  = hmp_qom_set,
+    },
+
+STEXI
+@item qom-set @var{path} @var{property} @var{value}
+Set QOM property @var{property} of object at location @var{path} to value @var{value}
 ETEXI
 
     {