[llvm] [Offload] Ensure to load images when the device is used (PR #103002)

[Johannes Doerfert via llvm-commits]

jdoerfert wrote:

> I believe device ctor / dtors are handled at image init / deinit time now. We used to init at first kernel / data call. I'm guessing this just expands that for external users?

Basically yes. This will load the image onto a device as soon as the device is "requested" (for whatever reason). The notable difference are API calls that interact with the device. Right now, they return wrong results, e.g., omp_get_mapped. 

https://github.com/llvm/llvm-project/pull/103002