Dead runtime-device memory wrappers in memory_op

[Cstandardlib]

Summary

source/source_base/module_device/memory_op.h:123-136 declares five wrappers that dispatch memory operations on runtime base_device::AbacusDevice_t values:
resize_memory, set_memory, synchronize_memory, cast_memory, delete_memory.

None of them has ever had a call site.

Details

PR #7941 fixed synchronize_memory and cast_memory, but why do they never cause any bugs?
It turns out that these APIs are dead and never used. Moreover, it is confusing to have TWO sets of memory_ops in our code:

wrapper	declared	defined	explicitly instantiated	call sites
resize_memory	memory_op.h:124	memory_op.cpp:530	no	0
set_memory	memory_op.h:127	memory_op.cpp:541	no	0
synchronize_memory	memory_op.h:130	memory_op.cpp:551	yes (:616-620)	0
cast_memory	memory_op.h:133	memory_op.cpp:578	yes (:622-629)	0
delete_memory	memory_op.h:136	memory_op.cpp:602	no	0

// source/source_base/module_device/memory_op.h
struct cast_memory_op

struct delete_memory_op
...
void cast_memory

void delete_memory

where the *_ops are what's been actually used.

It should be totally removed from our codebase.