Unit Tests Revamp w/ Testing Documentation Improvements

[MagusWyvern]

This PR is heavily aimed at fixing the entire tests folder so that all of them are passing. This is accomplished by either updating the code to use the correct Python3 syntax or rewriting function calls to reflect any changes in the malaya library itself.

In the future, we'll be able to use the unit tests to write automatic CI status checks for upcoming PRs. This PR comes with a dedicated wiki page for unit tests.