fix(build): Update contributing.md and fix npm ci

Changes:
- Update CONTRIBUTING.md to use npm ci
- Add a preinstall task to install all of the sub packages

closes aws-powertools#415

Author: michaelbrewer

Diff for: package.json

@@ -8,6 +8,7 @@
     "packages/*"
   ],
   "scripts": {
+    "preinstall": "(cd packages/commons && npm ci); (cd packages/logger && npm ci); (cd packages/metrics && npm ci); (cd packages/tracing && npm ci);",
     "init-environment": "husky install",
     "test": "npm run lerna-test",
     "commit": "commit",
@@ -26,8 +27,7 @@
     "docs-buildDockerImage": "docker build -t powertool-typescript/docs ./docs/",
     "docs-runLocalDocker": "docker run --rm -it -p 8000:8000 -v ${PWD}:/docs powertool-typescript/docs",
     "docs-generateApiDoc": "typedoc .",
-    "docs-runLocalApiDoc": "npx live-server api",
-    "preinstall": "(cd packages/commons && npm ci); (cd packages/logger && npm ci); (cd packages/metrics && npm ci); (cd packages/tracing && npm ci);"
+    "docs-runLocalApiDoc": "npx live-server api"
   },
   "repository": {
     "type": "git",