pybind11

Address regression introduced in #5381 (#5396)

* Incomplete attempt to address regression introduced in #5381

* style: pre-commit fixes

* Revert "style: pre-commit fixes"

This reverts commit 9d107d2f751d76b2c26e90cd08d2ac163022c873.

* Revert "Incomplete attempt to address regression introduced in #5381"

This reverts commit 8cf1cdbc96ac326ff6d64a36ea291472f74c016f.

* Simpler fix for the regression introduced in #5381

* style: pre-commit fixes

* Added if constexpr workaround

This can probably be done better but at least this is a start.

* style: pre-commit fixes

* Replace if constexpr with template struct

if constexpr was not added until C++ 17.
I think this should do the same thing as before.

* style: pre-commit fixes

* Made comment clearer

* Added test cases

* style: pre-commit fixes

* Fixed is_same_or_base_of reference

* style: pre-commit fixes

* Added static assert messages

* style: pre-commit fixes

* Replaced typedef with using

* style: pre-commit fixes

* Back out `ForwardClassPtr` (to be discussed separately). Tested locally with clang-tidy.

* Shuffle new `static_assert()` and leave error messages blank (they are more distracting than helpful here).

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: gentlegiantJGC <gentlegiantJGC@users.noreply.github.com>
Co-authored-by: Ralf W. Grosse-Kunstleve <rgrossekunst@nvidia.com>