Fix: Memory leak in ICUParagraphLayout::NextLine() (#11895)

This function calls icu::BreakIterator::createLineInstance() but does not clean up after it.

Instead use a static instance that is cloned (for thread-safety) and deleted as necessary.

src/strings.cpp

@@ -37,6 +37,7 @@
 #include "network/network_content_gui.h"
 #include "newgrf_engine.h"
 #include "core/backup_type.hpp"
+#include "gfx_layout.h"
 #include <stack>
 #include <charconv>
 
@@ -1976,6 +1977,8 @@ bool ReadLanguagePack(const LanguageMetadata *lang)
 	}
 #endif /* WITH_ICU_I18N */
 
+	Layouter::Initialize();
+
 	/* Some lists need to be sorted again after a language change. */
 	ReconsiderGameScriptLanguage();
 	InitializeSortedCargoSpecs();