[Driver] Some SYCL-specific options propagate to FE in non-SYCL mode

Generally, when no `fsycl` is given and a SYCL-specific option is passed by the user, we error out (e.g. as is the case with `-fsycl-targets`). `-sycl-std` is a known exception, however:
```bash
clang++ test.cpp -sycl-std=2017 -### 2>&1 | grep sycl-std
```
will show the option's presence in the FE call. It doesn't seem to affect the compilation, therefore is a minor issue by itself.

We should revise the list of SYCL-specific options, making sure that those affecting the compilation require `-fsycl`, and the less critical ones are ignored with a warning.