[SYCL][ABI-break] Cleanup ABI entries (#20846)
Remove unused ABI entries and implement couple of TODOs:
* Renamed `getOrInsertHandlerKernelBundlePtr` to
`getOrInsertHandlerKernelBundle`
* Employed inline namespace for `SubmissionInfo`
Co-authored-by: Steffen Larsen <steffen.larsen@intel.com>
