[CI][NFC] Add placeholder workflow file for testing PR #19280 (#19281)

This PR allows changes in #19280 to be
tested. This PR will be open for merging if changes in #19280 are
approved.

Author: ianayl

.github/workflows/sycl-nightly-benchmarking.yml

@@ -0,0 +1,7 @@
+name: SYCL Nightly Benchmarking
+
+# Placeholder workflow for testing https://github.com/intel/llvm/pull/19280
+
+jobs:
+  do-nothing:
+    runs-on: ubuntu-latest