Common/MsgHandler: Add fmt-capable variants of the alert macros

Adds an interface that uses fmt under the hood, which is much more
flexible than printf, particularly for localization purposes, given fmt
supports positional formatters in a cross-platform manner out of the box
with no configuration necessary.

Languages/update-source-strings.sh

@@ -9,9 +9,24 @@ cd "$(dirname "$0")/.."
 SRCDIR=Source
 find $SRCDIR -name '*.cpp' -o -name '*.h' -o -name '*.c' | \
 	xgettext -s -p ./Languages/po -o dolphin-emu.pot --package-name="Dolphin Emulator" \
-	--keyword=_ --keyword=wxTRANSLATE --keyword=SuccessAlertT --keyword=PanicAlertT \
-	--keyword=PanicYesNoT --keyword=AskYesNoT --keyword=CriticalAlertT --keyword=GetStringT \
-	--keyword=_trans --keyword=tr:1,1t --keyword=tr:1,2c --keyword=QT_TR_NOOP --keyword=FmtFormatT \
+	--keyword=_ \
+	--keyword=wxTRANSLATE \
+	--keyword=AskYesNoT \
+	--keyword=AskYesNoFmtT \
+	--keyword=CriticalAlertT \
+	--keyword=CriticalAlertFmtT \
+	--keyword=PanicAlertT \
+	--keyword=PanicAlertFmtT \
+	--keyword=PanicYesNoT \
+	--keyword=PanicYesNoFmtT \
+	--keyword=SuccessAlertT \
+	--keyword=SuccessAlertFmtT \
+	--keyword=GetStringT \
+	--keyword=_trans \
+	--keyword=tr:1,1t \
+	--keyword=tr:1,2c \
+	--keyword=QT_TR_NOOP \
+	--keyword=FmtFormatT \
 	--add-comments=i18n --from-code=utf-8 -f -
 
 # Copy strings from qt-strings.pot to dolphin-emu.pot