urProgramBuild doesnt take a list of devices, like piProgramBuild

piProgramBuild receives a list of devices, while urProgramBuild does not. This produces a series of issues when a UR program needs to be created for a specific device.

So we need to define a new API, something like urProgramBuildExp to pass this list (please see here https://github.com/oneapi-src/unified-runtime/pull/911)

Another alternative is to add numDevices and phDevices to existing urProgramBuild:

• if numDevices is zero, the urProgramBuild retains current behavior, where program is build for all devices in the context
• if numDevices is non-zero, then urProgramBuild builds only for those devices.

Other suggestions are welcome.