add github actions for coding standard

Author: torhoehn

.github/workflows/coding-standard.yml

@@ -0,0 +1,14 @@
+name: ExtDN M2 Coding Standard
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  static:
+    name: M2 Coding Standard
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: extdn/github-actions-m2/magento-coding-standard@master

.github/workflows/copy-paste-detector.yml

@@ -0,0 +1,14 @@
+name: ExtDN M2 Copy Paste Detector
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  phpmd:
+    name: M2 Copy Paste Detector
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: extdn/github-actions-m2/magento-copy-paste-detector@master

.github/workflows/mess-detector.yml

@@ -0,0 +1,14 @@
+name: ExtDN M2 Mess Detector
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  phpmd:
+    name: M2 Mess Detector
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: extdn/github-actions-m2/magento-mess-detector@master

.github/workflows/phpstan.yml

@@ -0,0 +1,16 @@
+name: ExtDN M2 PHPStan
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  phpstan:
+    name: M2 PHPStan
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: extdn/github-actions-m2/magento-phpstan@master
+        with:
+          composer_name: foo/magento2-foobar