Improve `sycl-ls` output when no devices are available

[0x12CC]

Is your feature request related to a problem? Please describe

Presently, when no SYCL devices are available, running sycl-ls produces no output. Many users have provided feedback saying they get stuck at this point during the initial system setup. A system with zero available SYCL devices nearly always implies some configuration issue. For non-experts, it can be challenging to figure out the problem without any feedback from the sycl-ls tool.

Describe the solution you would like

We should provide some guidance to users when the runtime detects no SYCL devices. At a minimum, the sycl-ls tool could reference some setup documentation. A better solution would be to present a checklist of runtime tests that are used to query the available devices. As an example, the tool could inform the user if any packages need to be installed, a dynamic library failed to load, or the devices are being filtered by an environment variable. The user is running sycl-ls on a CPU so we should at least be able to guide them towards configuring the OpenCL CPU backend correctly.

Describe alternatives you have considered

Current alternatives are the following:

1. Run sycl-ls with the --verbose flag. This provides some additional information but is rarely useful for understanding why SYCL devices are not listed.
2. Run sycl-ls with the strace tool. This will produce an output of all of the system calls made by the tool and can point towards missing dependencies.

Additional context

No response