Build JS Clarinet test lib on top the core SDK

[hugocaillard]

The clarinet core JS SDK allows to load a clarinet session and interact with it (call functions, get contracts interfaces - ABI, get devnet.toml accounts and get the assets per addresses/contracts).

While the core SDK will allow to interact with a session in many ways, the test kit should provide a nice and easy way to test clarity contracts. It will be the recommended way to test clarinet projects.

• The test kit library expose a more developer friendly testing API thanks to helpers and wrappers around core
• Should handle code coverage out of the box in a an easy way
• Some assertion features for clarity values and events.
• We should also provide a clarinet 1 compatibility layer (test-compat) on top of core and test-kit that will implement the exact same API as the Deno testing library (Clarinet.test, String.prototype.expect*) to ease the transition of existing projects from the clarinet 1 / deno testing framework to the new one.