Add Fake Wasa Classes

[willemneal]

To test our assemblyscript programs it is useful to mock or "fake" the classes that use the wasi imports. That way the program thinks it's running in a real environment, but you can mock the data, e.g. reading and writing to a file.

See wasa.ts. To work on one open an issue.

• IO
• Console
• Random
• Date
• Process
• EnvironEntry
• Environ
• CommandLine
• Filesystem

Some of these depend on others.

[shlokKh]

I'm confused as to what needs to be done for this part, all the fake classes already seem to be implemented in the wasa.ts file?