Add modules support (#1015)

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

src/ftxui/screen/color.cppm

@@ -0,0 +1,22 @@
+/**
+ * @file color.cppm
+ * @brief Module file for the Color class of the Screen module
+ */
+
+module;
+
+#include <ftxui/screen/color.hpp>
+
+export module ftxui.screen.color;
+
+/**
+ * @namespace ftxui
+ * @brief The FTXUI ftxui:: namespace
+ */
+export namespace ftxui {
+    using ftxui::Color;
+
+    inline namespace literals {
+        using ftxui::literals::operator""_rgb;
+    }
+}