Feature: drop ICU-lx in favour of directly interfacing with harfbuzz

This means we have RTL support again with ICU 58+. It makes use of:
- ICU for bidi-itemization
- ICU for script-itemization
- OpenTTD for style-itemization
- harfbuzz for shaping

CMakeLists.txt

@@ -143,7 +143,8 @@ if(NOT OPTION_DEDICATED)
             endif()
             find_package(Fluidsynth)
             find_package(Fontconfig)
-            find_package(ICU OPTIONAL_COMPONENTS i18n lx)
+            find_package(Harfbuzz)
+            find_package(ICU OPTIONAL_COMPONENTS i18n)
         endif()
     endif()
 endif()
@@ -178,6 +179,12 @@ if(UNIX AND NOT APPLE AND NOT OPTION_DEDICATED)
     if(NOT SDL_FOUND AND NOT SDL2_FOUND AND NOT ALLEGRO_FOUND)
         message(FATAL_ERROR "SDL, SDL2 or Allegro is required for this platform")
     endif()
+    if(HARFBUZZ_FOUND AND NOT ICU_i18n_FOUND)
+        message(WARNING "HarfBuzz depends on ICU i18n to function; HarfBuzz will be disabled")
+    endif()
+    if(NOT HARFBUZZ_FOUND)
+        message(WARNING "Without HarfBuzz and ICU i18n the game will not be able to render right-to-left languages correctly")
+    endif()
 endif()
 if(APPLE)
     if(NOT AUDIOTOOLBOX_LIBRARY)
@@ -289,7 +296,7 @@ if(NOT OPTION_DEDICATED)
     link_package(Allegro)
     link_package(FREETYPE TARGET Freetype::Freetype)
     link_package(Fontconfig TARGET Fontconfig::Fontconfig)
-    link_package(ICU_lx)
+    link_package(Harfbuzz TARGET harfbuzz::harfbuzz)
     link_package(ICU_i18n)
 
     if(SDL2_FOUND AND OPENGL_FOUND AND UNIX)