Add deployment field to job environment

Add support for the 'deployment' boolean property under 'environment:' in
workflow YAML. When set to false, the job accesses environment protection
rules and secrets without creating a deployment record.

Changes:
- Add 'deployment' to job-environment-mapping schema (workflow-v1.0.json)
- Add 'deployment' to ActionsEnvironmentReference type
- Add feature-gated parsing in environment converter
- Add 'allowDeploymentKeyword' experimental feature flag
- Add xlang test data for enabled/disabled feature flag scenarios

workflow-parser/testdata/reader/errors-job-environment-deployment-disabled-feature.yml

@@ -0,0 +1,21 @@
+include-source: false # Drop file/line/col from output
+skip:
+  - C#
+---
+on: push
+jobs:
+  build:
+    environment:
+      name: production
+      deployment: false
+    runs-on: ubuntu-latest
+    steps:
+      - run: echo hi
+---
+{
+  "errors": [
+    {
+      "Message": ".github/workflows/errors-job-environment-deployment-disabled-feature.yml (Line: 6, Col: 7): The key 'deployment' is not allowed"
+    }
+  ]
+}