Validates yaml schemas from engine (#10133)

Co-authored-by: Paul Ritter <ritter.paul1@gmail.com>

.github/workflows/validate_mapfiles.yml

@@ -0,0 +1,18 @@
+name: YAML schema validator
+on: [push]
+
+jobs:
+  yaml-schema-validation:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Setup Submodule
+      run: git submodule update --init
+    - name: Pull engine updates
+      uses: space-wizards/submodule-dependency@v0.1.5
+    - uses: PaulRitter/yaml-schema-validator@v1
+      with:
+        schema: RobustToolbox/Schemas/mapfile.yml
+        path_pattern: .*Resources/Maps/.*
+        validators_path: RobustToolbox/Schemas/mapfile_validators.py
+        validators_requirements: RobustToolbox/Schemas/mapfile_requirements.txt