Enable arm64 atomics for standalone GC

[kunalspathak]

As part of #71169, atomics instructions are added for GC code. It is turned off by default for standalone GC. This issue tracks to enable it by having the detection functionality in isa_detection.cpp and probably have a separate flag g_gc_arm64_atomics_present different from g_arm64_atomics_present that is used in GC code base.

cc: @Maoni0

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Issue Details

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As part of #71169, atomics instructions are added for GC code. It is turned off by default for standalone GC. This issue tracks to enable it by having the detection functionality in isa_detection.cpp and probably have a separate flag g_gc_arm64_atomics_present different from g_arm64_atomics_present that is used in GC code base.

cc: @Maoni0

Author:	kunalspathak
Assignees:	-
Labels:	area-GC-coreclr
Milestone:	-

[kunalspathak]

Since #71169 is not done, this is not needed.