Build system: add options to output the content and media files directly to separate output folders

[NathanLovato]

Currently the build system outputs everything to a "dist" folder containing both the prepared content and media files. Before media files were grouped with content so this allowed outputting directly to the website. Now, we output media files to a static folder to make builds more efficient in nextjs.

We could add options to instantly output everything to the desired folders: one output path for content, another for media files.