[Commands] Add #setaltcurrency Command. (#1850)

* [Commands] Add #setaltcurrency Command.
- Add #setaltcurrency [Currency ID] [Amount] command to allow you to set a specific alternate currency to a value.
- Add Zone::GetCurrencyID() and Zone::GetCurrencyItemID() helper methods.
- Cleanup loops through zone->AlternateCurrencies.
- Utilize helper methods where necessary.
- Convert old methods parameters and return values from int to uint32 where necessary.

* Typo.

zone/gm_commands/setaltcurrency.cpp

@@ -0,0 +1,59 @@
+#include "../client.h"
+
+void command_setaltcurrency(Client *c, const Seperator *sep)
+{
+	int arguments = sep->argnum;
+	if (
+		arguments < 2 ||
+		!sep->IsNumber(1) ||
+		!sep->IsNumber(2)
+	) {
+		c->Message(Chat::White, "Command Syntax: #setaltcurrency [Currency ID] [Amount]");
+		return;
+	}
+
+	auto target = c;
+	if (c->GetTarget() && c->GetTarget()->IsClient()) {
+		target = c->GetTarget()->CastToClient();
+	}
+
+	auto currency_id = std::stoul(sep->arg[1]);
+	auto amount = static_cast<int>(std::min(std::stoll(sep->arg[2]), (long long) 2000000000));
+	uint32 currency_item_id = zone->GetCurrencyItemID(currency_id);
+	if (!currency_item_id) {
+		c->Message(
+			Chat::White,
+			fmt::format(
+				"Currency ID {} could not be found.",
+				currency_id
+			).c_str()
+		);
+		return;
+	}
+
+	target->SetAlternateCurrencyValue(currency_id, amount);
+	
+	c->Message(
+		Chat::White,
+		fmt::format(
+			"{} now {} {} {}.",
+			(
+				c == target ?
+				"You" :
+				fmt::format(
+					"{} ({})",
+					target->GetCleanName(),
+					target->GetID()
+				)
+			),
+			c == target ? "have" : "has",
+			(
+				amount ?
+				std::to_string(amount) :
+				"no"
+			),
+			database.CreateItemLink(currency_item_id)
+		).c_str()
+	);
+}
+