Avoid extern includes in standard library IO

Right now, we are using `extern include` in the standard library for IO functionality. We would like to inline the files `libraries/llvm/io.ll` and also `libraries/js/io.js` into the position where they are included. We could actually be more fine-grained and inline the parts of them closer to where they are used.

Moreover, we have to be more fine-grained with regard to what runs on node only versus in the web.

Start by tracing how extern includes are handled for the standard library, then inspect libraries/llvm/io.ll and libraries/js/io.js and where they are included. Determine how to inline the IO contents or smaller parts at their use sites while separating node-only behavior from web behavior; done means the standard library no longer relies on these extern includes and both environments retain the required IO functionality.

Written by the indexing model from the issue text.