astructs: stop re-exporting AccessStruct

AccessStruct is no longer used by the vamos runtime or allocator.
Keeping it in the umbrella astructs import kept the obsolete helper in
the default public surface even after the caller cleanup was finished.

Stop re-exporting AccessStruct from astructs/__init__.py and update
the dedicated unit test to import it from its direct module instead.
This keeps the standalone compatibility module available without
presenting it as part of the primary typed-struct API.

Author: reinauer

amitools/vamos/astructs/__init__.py

@@ -1,4 +1,3 @@
-from .access import AccessStruct
 from .astruct import AmigaStruct, AmigaStructTypes, APTR_SELF, BPTR_SELF
 from .astructdef import AmigaStructDef, AmigaClassDef
 from .scalar import ULONG, LONG, UWORD, WORD, UBYTE, BYTE, ScalarType

test/unit/astructs_access.py

@@ -1,6 +1,5 @@
 import pytest
 from amitools.vamos.astructs import (
-    AccessStruct,
     AmigaStruct,
     AmigaStructDef,
     APTR_SELF,
@@ -11,6 +10,7 @@
     CSTR,
     BPTR_VOID,
 )
+from amitools.vamos.astructs.access import AccessStruct
 from amitools.vamos.machine.mock import MockMemory