[Commands] Add #clearxtargets Command (#3833)

# Perl
- Add `$client->ClearXTargets()`.

# Lua
- Add `client:ClearXTargets()`.

# Notes
- Add `#clearxtargets` command for players.
- Allows operators/players to clear their XTargets if something get stuck on it.

zone/gm_commands/clearxtargets.cpp

@@ -0,0 +1,50 @@
+#include "../client.h"
+
+void command_clearxtargets(Client *c, const Seperator *sep)
+{
+	const int reuse_timer = RuleI(Character, ClearXTargetDelay);
+
+	const int arguments = sep->argnum;
+	if (arguments) {
+		const bool is_help = !strcasecmp(sep->arg[1], "help");
+
+		if (is_help) {
+			c->Message(Chat::White, "Usage: #clearxtargets");
+			c->Message(
+				Chat::White,
+				"Note: Use this if your Extended Target window is bugged or has lingering targets that are invalid."
+			);
+			if (reuse_timer) {
+				c->Message(
+					Chat::White,
+					fmt::format(
+						"Note: This can only be used every {}.",
+						Strings::SecondsToTime(reuse_timer)
+					).c_str()
+				);
+			}
+			return;
+		}
+	}
+
+	if (reuse_timer) {
+		const uint32 time_left = c->GetPTimers().GetRemainingTime(pTimerClearXTarget);
+		if (!c->GetPTimers().Expired(&database, pTimerClearXTarget, false)) {
+			c->Message(
+				Chat::White,
+				fmt::format(
+					"You must wait {} before using this command again.",
+					Strings::SecondsToTime(time_left)
+				).c_str()
+			);
+			return;
+		}
+	}
+
+	c->ClearXTargets();
+	c->Message(Chat::White, "Extended Target window has been cleared.");
+
+	if (reuse_timer) {
+		c->GetPTimers().Start(pTimerClearXTarget, reuse_timer);
+	}
+}