Compile specification as part of CI (#5817) (#5826)

It can generate TypeScript errors that are not otherwise caught.

(cherry picked from commit e4dab78)

Co-authored-by: Quentin Pradet <quentin.pradet@elastic.co>

Author: github-actions[bot]

.github/workflows/code-format.yml

@@ -21,5 +21,6 @@ jobs:
 
     - name: Code style check
       run: |
+        npm run compile:specification --prefix compiler
         npm run format:check --prefix compiler