swap tests to use jest and separate e2e and unit tests

[OliverMKing]

Description

Swap tests to use jest and separate them into e2e tests and unit tests. Jest is preferred over mocha because that's what our team has experience with. Separating e2e and unit tests makes sense to reduce testing feedback loop time + makes the repository more organized.

microsoft/vscode-test#59 Here's some discussion on how to do it for vs-code (and some interesting jest vs mocha discussion). In most metrics jest has greatly surpassed mocha.

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

These are testing changes. They run both locally and on the github runner. They have been checked in both failure and success cases. If tests fail, the cli returns a non 0 exit code and the opposite for successes.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[OliverMKing]

This isn't worth it. Let's just use Mocha 🐙.