Add lock command for invoking swaylock_command

Add lock command to be able to bind a key to invoke the lock command
specified by swaylock_command

sway/commands.c

@@ -167,6 +167,7 @@ static struct cmd_handler command_handlers[] = {
 	{ "focus", cmd_focus },
 	{ "kill", cmd_kill },
 	{ "layout", cmd_layout },
+	{ "lock", cmd_lock },
 	{ "move", cmd_move },
 	{ "opacity", cmd_opacity },
 	{ "reload", cmd_reload },

sway/commands/lock.c

@@ -0,0 +1,11 @@
+#include <wlr/util/log.h>
+#include "log.h"
+#include "sway/commands.h"
+#include "sway/idle.h"
+
+struct cmd_results *cmd_lock(int argc, char **argv) {
+
+	invoke_swaylock();
+
+	return cmd_results_new(CMD_SUCCESS, NULL, NULL);
+}

sway/meson.build

@@ -37,6 +37,7 @@ sway_sources = files(
 	'commands/focus_follows_mouse.c',
 	'commands/fullscreen.c',
 	'commands/kill.c',
+	'commands/lock.c',
 	'commands/opacity.c',
 	'commands/include.c',
 	'commands/input.c',