ci: add capability to handle container initialisation steps to sync.py

pr-checks/checks/test-proxy.yml

@@ -4,7 +4,17 @@ versions: ["linked", "nightly-latest"]
 operatingSystems: ["ubuntu"]
 container:
   image: ubuntu:22.04
-  options: --dns 127.0.0.1
+  options: --dns 8.8.8.8
+container-init-steps:
+  name: Set up GitHub CLI
+  run: |
+    apt update
+    apt install -y curl libreadline8 gnupg2 software-properties-common zstd
+    curl -fsSL https://cli.github.com/packages/githubcli-archive-keyring.gpg | dd of=/usr/share/keyrings/githubcli-archive-keyring.gpg
+    apt-key add /usr/share/keyrings/githubcli-archive-keyring.gpg
+    apt-add-repository https://cli.github.com/packages
+    apt install -y gh
+  env: {}
 services:
   squid-proxy:
     image: ubuntu/squid:latest

pr-checks/sync.py

@@ -124,6 +124,12 @@ for file in (this_dir / 'checks').glob('*.yml'):
         },
     ]
 
+    # If container initialisation steps are present in the check specification,
+    # make sure to execute them first.
+    if 'container' in checkSpecification and 'container-init-steps' in checkSpecification:
+        steps.insert(0, checkSpecification['container-init-steps'])
+
+
     steps.extend(checkSpecification['steps'])
 
     checkJob = {