core.common: move assert_subpackage to my.core.internal

my/core/internal.py

@@ -0,0 +1,9 @@
+"""
+Utils specific to hpi core, shouldn't really be used by HPI modules
+"""
+
+
+def assert_subpackage(name: str) -> None:
+    # can lead to some unexpected issues if you 'import cachew' which being in my/core directory.. so let's protect against it
+    # NOTE: if we use overlay, name can be smth like my.origg.my.core.cachew ...
+    assert name == '__main__' or 'my.core' in name, f'Expected module __name__ ({name}) to be __main__ or start with my.core'