Add modules support (#1015)

Add experimental C++20 module suppport.
Co-authored-by: ArthurSonzogni <sonzogniarthur@gmail.com>

tools/generate_examples_modules.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+
+# Generate ./examples_modules from ./examples to using C++20 modules instead of 
+# #includes for ftxui.
+# This is useful for testing ftxui with modules. This ensures we don't forget
+# to update the FTXUI modules when adding new features to FTXUI.
+
+echo "Generating ./examples_modules"
+rm -rf ./examples_modules
+cp -r ./examples ./examples_modules
+
+for file in ./examples_modules/**/*.cpp; do
+  echo "Generating $file"
+
+  sed -i '/#include "ftxui/d' "$file"
+  sed -i '/#include <ftxui/d' "$file"
+  sed -i '1i\import ftxui.component;' "$file"
+  sed -i '2i\import ftxui.dom;' "$file"
+  sed -i '3i\import ftxui.screen;' "$file"
+  sed -i '4i\import ftxui.util;' "$file"
+  sed -i '5i\\' "$file"
+done
+
+# Modify the CMakeLists.txt file to link against ftxui-modules
+sed -i 's/${DIRECTORY_LIB}/ftxui-modules/g' ./examples_modules/CMakeLists.txt
+sed -i 's/ftxui_example_/ftxui_modules_example_/g' ./examples_modules/CMakeLists.txt
+
+
+