refactor: inline handle_panic into macro output

[davidhewitt]

I was looking at cargo llvm-lines output one last time, and a major contributor to llvm line count seems to be pyo3::callback::handle_panic.

Because it takes the whole function body as a closure, it's going to be instantiated separately for each pyfunction. Inlining it into the macro outputs leads to about a 10% reduction in llvm line counts for the pytests crate.

cd pytests; cargo llvm-lines | head -n 10 on main:

  Lines         Copies       Function name
  -----         ------       -------------
  59320 (100%)  2227 (100%)  (TOTAL)
   3546 (6.0%)    62 (2.8%)  std::panicking::try
   3223 (5.4%)    62 (2.8%)  pyo3::callback::handle_panic
   2341 (3.9%)    56 (2.5%)  <core::result::Result<T,E> as core::ops::try_trait::Try>::branch
   2046 (3.4%)    62 (2.8%)  std::panicking::try::do_catch
   1820 (3.1%)    10 (0.4%)  pyo3::types::module::PyModule::add_wrapped
   1759 (3.0%)    62 (2.8%)  std::panicking::try::do_call
   1647 (2.8%)     3 (0.1%)  pyo3::impl_::extract_argument::FunctionDescription::extract_arguments_tuple_dict

On this branch:

  Lines         Copies       Function name
  -----         ------       -------------
  54716 (100%)  1987 (100%)  (TOTAL)
   2963 (5.4%)    51 (2.6%)  std::panicking::try
   2341 (4.3%)    56 (2.8%)  <core::result::Result<T,E> as core::ops::try_trait::Try>::branch
   1820 (3.3%)    10 (0.5%)  pyo3::types::module::PyModule::add_wrapped
   1683 (3.1%)    51 (2.6%)  std::panicking::try::do_catch
   1647 (3.0%)     3 (0.2%)  pyo3::impl_::extract_argument::FunctionDescription::extract_arguments_tuple_dict
   1473 (2.7%)    51 (2.6%)  std::panicking::try::do_call
   1342 (2.5%)    17 (0.9%)  pyo3::impl_::extract_argument::extract_argument