CI: Move sanitizer output into a separate CI step

Instead of writing ASAN and UBSAN output into the same stream we use for
test logging, direct them to two log files, asan.log and ubsan.log, and
then output them in a separate CI job that runs afterwards. This should
hopefully make it easier to see which tests are failing, without losing
any benefits.

.github/workflows/lagom-template.yml

@@ -185,6 +185,8 @@ jobs:
         run: ctest --preset Sanitizer --output-on-failure --test-dir Build
         env:
           TESTS_ONLY: 1
+          ASAN_OPTIONS: 'log_path=asan.log'
+          UBSAN_OPTIONS: 'log_path=ubsan.log'
 
       - name: Upload LibWeb Test Artifacts
         if: ${{ always() && inputs.fuzzer == 'NO_FUZZ' }}
@@ -195,6 +197,30 @@ jobs:
           retention-days: 7
           if-no-files-found: ignore
 
+      - name: Sanitizer Output
+        if: ${{ always() && inputs.fuzzer == 'NO_FUZZ' }}
+        working-directory: ${{ github.workspace }}
+        run: |
+          SANITIZER_PROBLEM=0
+          if [ -e asan.log ]; then
+            echo '::group::ASAN'
+            cat asan.log
+            echo '::endgroup::'
+            SANITIZER_PROBLEM=1
+          fi
+          if [ -e ubsan.log ]; then
+            echo '::group::UBSAN'
+            cat ubsan.log
+            echo '::endgroup::'
+            SANITIZER_PROBLEM=1
+          fi
+          if [ "$SANITIZER_PROBLEM" = 1 ]; then
+            return 1
+          else
+            echo 'No sanitizer issues found.'
+            return 0
+          fi
+
       - name: Lints
         if: ${{ inputs.os_name == 'Linux' && inputs.fuzzer == 'NO_FUZZ' }}
         working-directory: ${{ github.workspace }}