[C++20] Enable C++20 + Fixes + FMT 9.1 (#2664)

* [CPP] Enable and build compliance with cpp20

* Windows build fix

* bump fmt version

* Updated fmt to 9.1, updated cmake minimum and verified preprocessor stuff works.

* Missing :

* Fix warning: top-level comma expression in array subscript is deprecated

* Fix warning: top-level comma expression in array subscript is deprecated

Co-authored-by: KimLS <KimLS@peqtgc.com>

zone/gm_commands/rules.cpp

@@ -73,7 +73,7 @@ void command_rules(Client *c, const Seperator *sep)
 			c->Message(
 				Chat::White,
 				fmt::format(
-					"Rule Set {} | {} ({})",
+					"Rule Set {} ({})",
 					e.second,
 					e.first
 				).c_str()

zone/gm_commands/zonelock.cpp

@@ -65,7 +65,7 @@ void command_zonelock(Client *c, const Seperator *sep)
 			c->Message(
 				Chat::White,
 				fmt::format(
-					"Usage: #zonelock {} [Zone ID] or #zonelock {} [Zone Short Name]",
+					"Usage: #zonelock {0} [Zone ID] or #zonelock {0} [Zone Short Name]",
 					is_lock ? "lock" : "unlock"
 				).c_str()
 			);