[Bindless][UR][LevelZero] Fix memory leak caused by not destroying sampler handles

[GeorgeWeb]

This PR fixes memory leaks where both UR and LevelZero sampler handles weren't being released and memory wasn't cleaned up appropriately when the bindless images object gets destroyed. The old SYCL 2020 images' sampler implementation is different as it is a self-managed RAII object which is not true for bindless images, hence we need to ensure, depending on the requirements of the backend/adapter API, to manage the lifetime of the sampler associated to the bindless image accordingly.

[igchor]

@GeorgeWeb How do other backends handle the lifetime of the sampler? The specification says nothing about urBindlessImagesSampledImageCreateEx taking ownership of the sampler. Isn't it possible for user to use the same sampler in multiple calls?

[GeorgeWeb]

@GeorgeWeb How do other backends handle the lifetime of the sampler? The specification says nothing about urBindlessImagesSampledImageCreateEx taking ownership of the sampler. Isn't it possible for user to use the same sampler in multiple calls?

Hey @igchor, you raise a good point and I think I didn't think this through fully. There is no precedent to take ownership of the sampler there. Actually this is not a Unified Runtime issue at the moment but rather it's just a bindless images issue definition, hence this PR currently may not be the right approach. It is, at the moment, absolutely plausible for the user to use the same sampler in multiple calls. However, I am not sure if this is the right direction or bindless images should just tie the sampler with the image altogether - that is a new point of discussion. Hence, I may close this PR altogether as we explore into defining and handling properly. Thanks.

[ProGTX]

Note this relates to oneapi-src/unified-runtime#1463