Handle not supported files when dragging to waveforms and spinnies #16248

Job	Run time
Ubuntu 22.04 (gcc)	9m 5s
Ubuntu 22.04 (Qt 6.2, gcc)	8m 10s
macOS 11 x64	17m 0s
macOS 11 arm64	12m 21s
Windows 2019 (MSVC)	13m 39s
Update manifest file on download server	32s
	1h 0m 47s

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