Upgrade to C++20 (#7554)

* Compile in C++20 mode

* Fix implicit lambda captures of `this` by `[=]`

Those implicit captures were deprecated in C++20

* Silence MSVC atomic std::shared_ptr warning

Unfortunately std::atomic<std::shared_ptr> (P0718R2) is not supported by
GCC until GCC 12 and still is not supported by Clang or Apple Clang, so
it looks like we will continue using std::atomic_load for the time being

* Use C++20 in RemoteVstPlugin

* Simplification

* Add comment

* Fix bitwise operations between different enumeration types

* Revert "Fix bitwise operations between different enumeration types"

This reverts commit d45792cd72.

* Use a helper function to combine keys and modifiers

* Remove AnalyzeTemporaryDtors from .clang-tidy

AnalyzeTemporaryDtors was deprecated in clang-tidy 16 and fully removed
in clang-tidy 18

* Use C++20 in .clang-format

* Use bitwise OR

Prevents issues if any enum flags in `args` have bits in common

plugins/SpectrumAnalyzer/SaControlsDialog.cpp

@@ -341,7 +341,6 @@ SaControlsDialog::SaControlsDialog(SaControls *controls, SaProcessor *processor)
 	m_waterfall = new SaWaterfallView(controls, processor, this);
 	display_splitter->addWidget(m_waterfall);
 	m_waterfall->setVisible(m_controls->m_waterfallModel.value());
-	connect(&controls->m_waterfallModel, &BoolModel::dataChanged, [=] {m_waterfall->updateVisibility();});
 }