bpo-46329: Streamline calling sequence a bit.

[markshannon]

This PR:

1. Removes the call_shape struct, except the kw_names field for keyword arguments.
2. Moves the KW_NAMES instruction before the PRECALL.
3. Changes the operand of CALL to match that of PRECALL.

See faster-cpython/ideas#267 (comment) for rationale.

https://bugs.python.org/issue46329

[bedevere-bot]

🤖 New build scheduled with the buildbot fleet by @markshannon for commit 77328c7 🤖

If you want to schedule another build, you need to add the ":hammer: test-with-buildbots" label again.

[markshannon]

The failures seem to be the usual asyncio flakiness and maybe a deadlock on the s390x buildbot.
The ARM64 Windows seems to be failing while linking.
All unrelated to this PR, although there are a couple of Windows compiler warnings to fix.