[OpenCL validation] Scope for Memory

_Scope_ for _Memory_ is generally limited to:
- **CrossDevice**
- **Device**
- **Workgroup**
- **Invocation**

On OpenCL 2.1/2.2:
- **Subgroup** is allowed as well (what to do with 2.0+cl_khr_subgroups?)

Review the OpenCL validation rules for Memory scope, especially the listed CrossDevice, Device, Workgroup, and Invocation scopes. Determine how OpenCL 2.1/2.2 and 2.0 with cl_khr_subgroups should treat Subgroup, then confirm the intended validation behavior and update the relevant validation coverage.

Written by the indexing model from the issue text.