Remove use of obsolete ImGui functions - v1.89 #490

Job	Run time
clang-format	11s
Windows MSVC Shared Release	1m 58s
Windows MSVC Shared Debug	1m 22s
Windows MSVC Static Release	2m 56s
Windows MSVC Static Debug	2m 33s
Windows ClangCL Shared Release	3m 14s
Windows ClangCL Shared Debug	2m 23s
Windows ClangCL Static Release	4m 44s
Windows ClangCL Static Debug	4m 3s
Windows Clang Shared Release	1m 16s
Windows Clang Shared Debug	2m 6s
Windows Clang Static Release	2m 42s
Windows Clang Static Debug	2m 27s
Linux GCC Shared Release	42s
Linux GCC Shared Debug	38s
Linux GCC Static Release	1m 17s
Linux GCC Static Debug	1m 6s
Linux Clang Shared Release	51s
Linux Clang Shared Debug	39s
Linux Clang Static Release	1m 17s
Linux Clang Static Debug	1m 13s
macOS Clang Shared Release	1m 25s
macOS Clang Shared Debug	1m 35s
macOS Clang Static Release	1m 17s
macOS Clang Static Debug	57s
	44m 52s

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