fix(build): add yarn lock to image before installing, add tmp files to docker ignore

.dockerignore

@@ -0,0 +1,7 @@
+.nyc_output/
+docs/api/
+node_modules/
+out/api
+out/cache/
+out/coverage/
+out/tmp/

Dockerfile

@@ -2,7 +2,9 @@ FROM node:12-stretch
 # alpine may be smaller, but comes with a 10-15% perf hit
 
 COPY package.json /app/package.json
-COPY out/ /app/out/
+COPY yarn.lock /app/yarn.lock
+
+COPY . /app
 
 WORKDIR /app