Kuzzle as a framework (#1641)

This PR introduce a new way to develop application with Kuzzle.
You can now develop an application in the same way you do with express-like framework instead of developing a business plugin injected in the core from the filesystem.

This is the first step, I will introduce new base class for plugin development in a subsequent PR.

Everything is backward compatible with the old plugin API (loading from the filesystem).

The kuzzle package now expose a Backend class. You can instantiate this class and define features before starting your kuzzle application.
This class has been written in Typescript to improve Developer Experience (DX).

Internally the Backend class is just a wrapper to create a Plugin (like any other plugin). The main difference is that plugin has the application flag.
Kuzzle ensure that only one application plugin can be loaded.

Author: Aschen

.ci/scripts/run-test-arm.sh

@@ -14,10 +14,12 @@ export NVM_DIR="$HOME/.nvm"
 . "$NVM_DIR/nvm.sh"
 nvm use $NODE_VERSION
 
-node bin/start-kuzzle-server --enable-plugins functional-test-plugin &
+npm run build
+
+node -r ts-node/register features-sdk/application/functional-tests-app.ts &
 
 echo "[$(date)] - Starting Kuzzle..."
 
 ./bin/wait-kuzzle
 
-npm run test:functional
+npm run $KUZZLE_FUNCTIONAL_TESTS

.ci/scripts/run-test.sh

@@ -13,11 +13,13 @@ n $NODE_VERSION
 
 npm install --silent --unsafe-perm
 
+npm run build
+
 ./docker/scripts/install-plugins.sh
 
 echo "[$(date)] - Starting Kuzzle..."
 
-node bin/start-kuzzle-server --enable-plugins functional-test-plugin &
+node -r ts-node/register features-sdk/application/functional-tests-app.ts &
 
 ./bin/wait-kuzzle