Cache node_modules, run npm install only once

.gitlab-ci.yml

 image: jhipster/jhipster:v7.6.0
 
 cache:
-  key: '$CI_COMMIT_REF_NAME'
-  paths:
-    - .maven/
+  - key: '$CI_COMMIT_REF_NAME'
+    paths:
+      - .maven/
+  - key:
+      files:
+        - package-lock.json
+    paths:
+      - node_modules/
+
 stages:
+  - setup
   - lint
   - build
   - test
@@ -12,10 +19,16 @@ stages:
   - package
   - release
   - deploy
+
 before_script:
   - export NG_CLI_ANALYTICS="false"
   - export MAVEN_USER_HOME=`pwd`/.maven
 
+npm-install:
+  stage: setup
+  script:
+    - npm install
+
 checkstyle:
   stage: lint
   script:
@@ -25,20 +38,18 @@ checkstyle:
 prettier:
   stage: lint
   script:
-    - npm install
     - npm run prettier:check
   allow_failure: true
-  needs: []
+  needs: [npm-install]
 
 eslint:
   stage: lint
   script:
-    - npm install
     # eslint exits 0 on warnings, this is a workaround to exit 1 when warnings are present.
     - 'npm run lint | tee lint.log'
     - "! grep -qE '✖ [0-9]+ problem' lint.log"
   allow_failure: true
-  needs: []
+  needs: [npm-install]
 
 maven-compile:
   stage: build
@@ -80,7 +91,6 @@ maven-test:
 frontend-test:
   stage: test
   script:
-    - npm install
     - npm test
   artifacts:
     reports:
@@ -91,7 +101,7 @@ frontend-test:
     when: always
     expire_in: 1 day
   allow_failure: true
-  needs: []
+  needs: [npm-install]
 
 sonar-analyze:
   stage: analyze