feat(api): make FreeType a toggleable option which is disabled by default (#254)

* deps(build): bump FreeType from 2.12.1 to 2.13.3

* fix(generator): add missing ImGuiFreeTypeBuilderFlags

* feat(generator): add possibility to provide additional defines specifically for AST

* feat(api): make FreeType optional and disabled by default

FreeType renderer is still included in the final build.
Its usage is toggleable and DISABLED by default.

.gitignore

@@ -25,7 +25,7 @@ logs/
 *.tar.gz
 *.rar
 *.gpg
-!vendor/freetype-2.12.1.tar.gz
+!vendor/*
 
 # Gradle
 .gradletasknamecache