[SYCL] Disable clang pedantic diagnostics in header/footer (#15171)
When -Wreserved-identifer or -Wold-style-cast is enabled, some of the
constructs used in
integration headers and footers for device_globals and host_pipes
trigger a diagnostic.
This change adds a pragma to the generated files that suppress the
diagnostic prior to
the construct and reenabled the diagnostic after.