Add GitHub action to check PRs for generated files

Checks and warns the user if he includes files in /dist or /markdown.

.github/workflows/check-for-generated-files.yml

@@ -0,0 +1,85 @@
+name: Check for Generated Files
+
+on:
+  # Triggers the workflow on push or pull request events but only for the dev branch
+  pull_request:
+    branches: [dev]
+
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+jobs:
+  checkFiles:
+    name: Check Files
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout files
+        uses: actions/checkout@v2
+
+      - name: Check bundle files
+        id: changed-bundle-files
+        uses: tj-actions/changed-files@v18.4
+        with:
+          files: |
+            dist/*
+            index.html
+            main.bundle.js
+            main.bundle.js.map
+
+      - name: Check documentation changes
+        id: changed-markdown-doc-files
+        uses: tj-actions/changed-files@v18.4
+        with:
+          files: |
+            markdown/*.md
+
+      - name: Warn when bundle files were changed
+        id: warn-bundles-changed
+        if: steps.changed-bundle-files.outputs.any_changed == 'true'
+        run: |
+          echo "One or more files in the bundle files were changed." >> warnings.txt
+
+      - name: Warn when documentation markdown files were changed
+        id: warn-markdown-changed
+        if: steps.changed-markdown-doc-files.outputs.any_changed == 'true'
+        run: |
+          echo "One or more files in the markdown documentation were changed." >> warnings.txt
+
+      - name: Print Warnings
+        id: get-warnings
+        run: |
+          if [ -f warnings.txt ]
+          then
+            echo "::set-output name=has_warnings::true"
+          else
+            echo "::set-output name=has_warnings::false"
+            touch warnings.txt
+          fi
+
+      - name: Get Comment Body
+        id: get-comment-body
+        if : steps.get-warnings.outputs.has_warnings == 'true'
+        run: |
+          cat warnings.txt > comment.txt
+          echo "" >> comment.txt
+          echo "Please do not commit files generated by webpack or generated markdown" >> comment.txt
+          echo "" >> comment.txt
+          echo "See [CONTRIBUTING.md](https://github.com/danielyxie/bitburner/blob/dev/doc/CONTRIBUTING.md) for details." >> comment.txt
+
+          body=$(cat comment.txt)
+          body="${body//'%'/'%25'}"
+          body="${body//$'\n'/'%0A'}"
+          body="${body//$'\r'/'%0D'}"
+
+          echo ::set-output name=body::$body
+      - name: Add github comment on problem
+        if : steps.get-warnings.outputs.has_warnings == 'true'
+        uses: peter-evans/commit-comment@v1
+        with:
+          body: ${{ steps.get-comment-body.outputs.body }}
+      - name: Flag as error
+        if : steps.get-warnings.outputs.has_warnings == 'true'
+        run: |
+          COMMIT_WARNINGS=$(cat warnings.txt)
+          echo "::warning:: $COMMIT_WARNINGS"
+          exit 1