Implement support for running MetaCall from python.exe and node.exe.

[viferga]

This feature implements support for this: #231 #460 (comment)

For implementing this, there's few details we will require:

• We must provide a mechanism to identify the host language
• We must define a way to initialize the loader as host
• We have to search for metacall library in the ports:
  • NodeJS
  • Python
  • Ruby
  • ... any other?
• We must modify the loaders in order to support host languages:
  • NodeJS
  • Python
  • Ruby
  • ... any other?
• We have to disable linking of the dependencies of the loaders, and move them to the configuration file, then load those dependencies before we initialize the loaders. This is a trick to allow loaders to have unresolved symbols and link to the host if the host language is the one running metacall, or link them against the dependencies.
• Bootstrapping of libmetacall.so and metacall.h by using the C Loader with metacall_load_from_package, so we do not need to implement any other API if the ports, we can bootstrap all of them easily.
• Make it work for:
  • Linux
  • Windows
  • MacOS
• Add full testing including integration tests with metacall/install and tests with multiple versions of NodeJS (compiled statically or dynamically), Python, and with different libc (Alpine) or different glibc versions.