Move the render context to its own folder.

We are going to have a lot of render context types because there are so many org-mode elements/objects so I'm moving it to a separate folder for organization.

src/main.rs

@@ -13,6 +13,7 @@ mod command;
 mod config;
 mod error;
 mod render;
+mod types;
 
 fn main() -> Result<ExitCode, CustomError> {
     let rt = tokio::runtime::Runtime::new()?;