move stat.FILE_ATTRIBUTE_* to _stat.pyi and fix availability (#6761)

tests/stubtest_allowlists/darwin.txt

@@ -37,6 +37,9 @@ fcntl.[A-Z0-9_]+
 os.SCHED_[A-Z_]+
 posix.SCHED_[A-Z_]+
 
+# Some of these exist on non-windows, but they are useless and this is not intended
+stat.FILE_ATTRIBUTE_[A-Z_]+
+
 # Loadable SQLite extensions are disabled on GitHub runners
 (sqlite3(.dbapi2)?.Connection.enable_load_extension)?
 (sqlite3(.dbapi2)?.Connection.load_extension)?

tests/stubtest_allowlists/linux.txt

@@ -40,6 +40,9 @@ fcntl.[A-Z0-9_]+
 os.SCHED_[A-Z_]+
 posix.SCHED_[A-Z_]+
 
+# Some of these exist on non-windows, but they are useless and this is not intended
+stat.FILE_ATTRIBUTE_[A-Z_]+
+
 # Loadable SQLite extensions are disabled on GitHub runners
 (sqlite3(.dbapi2)?.Connection.enable_load_extension)?
 (sqlite3(.dbapi2)?.Connection.load_extension)?

tests/stubtest_allowlists/win32.txt

@@ -1,6 +1,5 @@
 _msi.MSI[A-Z_]+
 _msi.PID_[A-Z_]+
-_stat.FILE_ATTRIBUTE_[A-Z_]+
 ctypes.GetLastError  # Is actually a pointer
 distutils.archive_util.getgrnam
 distutils.archive_util.getpwnam