Port pyodide to slapos
The pyodide buildout script contains two separate parts, one is base on "section", which is my first attempt for port pyodide to slapos, but I found it is not easy to do some fine-grained control. Unlike other software, pyodide put all dependencies into its own directory and apply its own custom patch when compiling rather than use submodule or another way to manage dependencies. So I switched to the second approach, which is basically written a Python script to control the compiling process. This is the one which could work currently. But I also kept the previous approach, I have no problem to remove it. Leave it here just for review.