Move libraries shims under src/native

[jkotas]

The current directory structure under src/libraries/native is confusing:

• The sub-directory names do not match the OSes where the shims are actually building.
• The shims are statically linked with the runtime in some configurations

We should consider moving all shims under src/native that seems to be the best place for unmanaged code shared between runtimes.

See #61852 (comment) for full context

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Issue Details

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The current directory structure under src/libraries/native is confusing:

• The sub-directory names do not match the OSes where the shims are actually building.
• The shims are statically linked with the runtime in some configurations

We should consider moving all shims under src/native that seems to be the best place for unmanaged code shared between runtimes.

See #61852 (comment) for full context

Author:	jkotas
Assignees:	-
Labels:	area-Infrastructure-libraries, untriaged
Milestone:	-