Removal of libsyclinterface DPCTLQueueMgr_* function related to device_context

[diptorupd]

The dpctl_sycl_queue_manager is a legacy of an old design in DPEP stack where we were planning to use a single Python context manager to define the execution queue globally. DPEP software stack now uses the array API compute follows data programming model, as such the following functions are redundant and should be removed:

DPCTL_API __dpctl_give DPCTLSyclQueueRef
DPCTLQueueMgr_GetCurrentQueue(void);

DPCTL_API size_t
DPCTLQueueMgr_GetQueueStackSize(void);

DPCTL_API bool
DPCTLQueueMgr_GlobalQueueIsCurrent(void);

DPCTL_API bool
DPCTLQueueMgr_IsCurrentQueue(__dpctl_keep const DPCTLSyclQueueRef QRef);

DPCTL_API void
DPCTLQueueMgr_PopQueue(void);

DPCTL_API void
DPCTLQueueMgr_PushQueue(__dpctl_keep const DPCTLSyclQueueRef QRef);

DPCTL_API void
DPCTLQueueMgr_SetGlobalQueue(__dpctl_keep const DPCTLSyclQueueRef QRef);

On dpctl's side I believe the whole dpctl._sycl_queue_manager.pyx can be removed.

Related #11, #410

[diptorupd]

@oleksandr-pavlyk @ndgrigorian If you agree, I can create a PR.

[ndgrigorian]

@oleksandr-pavlyk @ndgrigorian If you agree, I can create a PR.

I agree, though dpnp may need to be changed before we can merge the PR. There should be nothing blocking opening a PR in dpctl.

[oleksandr-pavlyk]

@diptorupd Resolving this issue would also close #11

[diptorupd]

@diptorupd Resolving this issue would also close #11

Of course, how can I miss that 😄