Adds CI hooks (#445)

Adds CI hooks

.github/workflows/postmerge-ci-buildspec.yml

+version: 0.2
+
+phases:
+  build:
+    commands:
+      - echo "Building a docker image"
+      - docker login -u \$oauthtoken -p $NGC_TOKEN nvcr.io
+      - docker build -t $IMAGE_NAME:latest-1.0 --build-arg ISAACSIM_VERSION_ARG=latest-4.0 --build-arg ISAACSIM_ROOT_PATH_ARG=/isaac-sim --build-arg ISAACLAB_PATH_ARG=/workspace/isaaclab --build-arg DOCKER_USER_HOME_ARG=/root -f docker/Dockerfile.base .
+      - echo "Pushing the docker image"
+      - docker push $IMAGE_NAME:latest-1.0
+      - docker tag $IMAGE_NAME:latest-1.0 $IMAGE_NAME:latest-1.0-b$CODEBUILD_BUILD_NUMBER
+      - docker push $IMAGE_NAME:latest-1.0-b$CODEBUILD_BUILD_NUMBER

.github/workflows/premerge-ci-buildspec.yml

+version: 0.2
+
+phases:
+  pre_build:
+    commands:
+      - echo "Launching EC2 instance to run tests"
+      - INSTANCE_ID=$(aws ec2 run-instances --image-id ami-05c519412a83cc291 --count 1 --instance-type g5.2xlarge --key-name production/ssh/isaaclab --security-group-ids sg-02617e4b8916794c4 --subnet-id subnet-0907ceaeb40fd9eac --block-device-mappings 'DeviceName=/dev/sda1,Ebs={VolumeSize=500}' --output text --query 'Instances[0].InstanceId')
+      - aws ec2 wait instance-running --instance-ids $INSTANCE_ID
+      - EC2_INSTANCE_IP=$(aws ec2 describe-instances --filters "Name=instance-state-name,Values=running" "Name=instance-id,Values=$INSTANCE_ID" --query 'Reservations[*].Instances[*].[PrivateIpAddress]' --output text)
+      - mkdir -p ~/.ssh
+      - aws ec2 describe-key-pairs --include-public-key --key-name production/ssh/isaaclab --query 'KeyPairs[0].PublicKey' --output text > ~/.ssh/id_rsa.pub
+      - aws secretsmanager get-secret-value --secret-id production/ssh/isaaclab --query SecretString --output text > ~/.ssh/id_rsa
+      - chmod 400 ~/.ssh/id_*
+      - echo "Host $EC2_INSTANCE_IP\n\tStrictHostKeyChecking no\n" >> ~/.ssh/config
+      - aws ec2-instance-connect send-ssh-public-key --instance-id $INSTANCE_ID --availability-zone us-west-2a --ssh-public-key file://~/.ssh/id_rsa.pub --instance-os-user ubuntu
+  build:
+    commands:
+      - echo "Running tests on EC2 instance"
+      - cd ..
+      - |
+        bash -c '
+        function retry_scp() {
+          local retries=5
+          local wait_time=10
+          local count=0
+          while [ $count -lt $retries ]; do
+            scp -r IsaacLab ubuntu@$EC2_INSTANCE_IP:~
+            if [ $? -eq 0 ]; then
+              echo "SCP command succeeded"
+              return 0
+            fi
+            count=$((count + 1))
+            echo "SCP command failed. Retrying in $wait_time seconds..."
+            sleep $wait_time
+          done
+          echo "SCP command failed after $retries attempts."
+          return 1
+        }
+        retry_scp
+        '
+      - ssh ubuntu@$EC2_INSTANCE_IP "docker login -u \\\$oauthtoken -p $NGC_TOKEN nvcr.io"
+      - ssh ubuntu@$EC2_INSTANCE_IP "cd IsaacLab;
+          docker build -t isaac-lab-dev --build-arg ISAACSIM_VERSION_ARG=4.0.0 --build-arg ISAACSIM_ROOT_PATH_ARG=/isaac-sim --build-arg ISAACLAB_PATH_ARG=/workspace/isaaclab --build-arg DOCKER_USER_HOME_ARG=/root -f docker/Dockerfile.base . ;
+          docker run --rm --entrypoint bash --gpus all --network=host --name isaac-lab-test isaac-lab-dev ./isaaclab.sh -t &&
+          exit $?"
+  post_build:
+    commands:
+      - echo "Terminating EC2 instance"
+      - aws ec2 terminate-instances --instance-ids $INSTANCE_ID