Support for Lua 5.4+ & C++17

[Flamefire]

Lua 5.4 actually sets nresults in lua_resume which previously was hardcoded to 1. This exposes an error with the start index passed to FunctionResultProxy::ReturnValue:

• The number of results is calculated as resultCount_ = lua_gettop(thread) + 1 - startIndex
• startIndex was set to nresult - (lua_gettop(state) + 1)
• as nresult == 1 is hardcoded: startIndex = -lua_gettop(state)
• So it follows: resultCount_ = lua_gettop(thread) + 1 + lua_gettop(state)` which doesn't hold (at least for 5.4)
• In fact the start index for results is constantly 1, index 0 is (likely) the success state (bool)

Finally in Lua 5.4.4+ lua_status inside the panic handler always returns "OK"

C++17 defines an output operator for nullptr so we need to remove the custom one.
GCC 13 warns about the "dangling references" returned by get<unique_ptr&> which is a false positive in this case.

Summary by Sourcery

Update the library to support Lua 5.4+ and C++17.

Bug Fixes:

• Fix an error in the FunctionResultProxy::ReturnValue calculation that was exposed by Lua 5.4's change to lua_resume.
• Handle the change in Lua 5.4.4+ where lua_status always returns "OK" inside the panic handler.

Enhancements:

• Improve coroutine support by enabling mixed yielding and receiving of parameters.

Tests:

• Add tests for mixed yielding and receiving of parameters in coroutines.
• Update tests to account for Lua 5.4.4+ panic handler behavior.

[sourcery-ai]

Reviewer's Guide by Sourcery

This pull request introduces support for Lua 5.4+ and C++17. The main changes include updating the coroutine handling to correctly manage the number of results returned by lua_resume in Lua 5.4+, handling a change in error status in Lua 5.4.4+ within the panic handler, removing a custom output operator for nullptr due to its definition in C++17, and addressing a false positive dangling reference warning in GCC 13.

File-Level Changes

Change	Details	Files
Updated coroutine handling to support Lua 5.4+	Modified lua_resume result handling to account for Lua 5.4+ changes in the number of returned results. Added tests for mixed yielding and receiving parameters in coroutines. Corrected the calculation of resultCount_ and startIndex in FunctionResultProxy::ReturnValue to handle Lua 5.4+ behavior where nresults is set by lua_resume. Ensured all results are on top of the thread stack after lua_resume.	test/test_04_lua_function.cpp include/kaguya/detail/lua_function_def.hpp
Handled Lua 5.4.4+ panic handler error status change	Added a check for LuaUnknownError and its message in the allocation error test to handle the case where lua_status returns "OK" inside the panic handler in Lua 5.4.4+.	test/test_06_state.cpp
Removed custom output operator for nullptr	Removed the custom output operator for nullptr as it is now defined in C++17.	test/test_util.hpp
Addressed GCC 13 dangling reference warning	Added a compiler flag -Wno-dangling-reference to suppress the false positive warning in GCC 13 about dangling references returned by get<unique_ptr&>.	CMakeLists.txt
Added support for Lua 5.4.7 in CI	Added Lua 5.4.7 to the test matrix in the CI workflow file.	.github/workflows/test.yml
Updated C++ standard to C++17	Modified CMakeLists.txt to use C++17.	CMakeLists.txt
Minor updates and fixes	Added #include <limits>.	test/test_01_primitive.cpp

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[sourcery-ai]

Hey @Flamefire - I've reviewed your changes and they look great!

Here's what I looked at during the review

• 🟡 General issues: 2 issues found
• 🟢 Security: all looks good
• 🟡 Testing: 1 issue found
• 🟢 Complexity: all looks good
• 🟢 Documentation: all looks good

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