gh-106581: Split `CALL_PY_EXACT_ARGS` into uops (#107760)

* Split `CALL_PY_EXACT_ARGS` into uops

This is only the first step for doing `CALL` in Tier 2.
The next step involves tracing into the called code object and back.
After that we'll have to do the remaining `CALL` specialization.
Finally we'll have to deal with `KW_NAMES`.

Note: this moves setting `frame->return_offset` directly in front of
`DISPATCH_INLINED()`, to make it easier to move it into `_PUSH_FRAME`.