Remove use of obsolete ImGui functions - v1.89 #489

Job	Run time
clang-format	7s
Windows MSVC Shared Release	1m 24s
Windows MSVC Shared Debug	1m 19s
Windows MSVC Static Release	1m 34s
Windows MSVC Static Debug	1m 35s
Windows ClangCL Shared Release	1m 46s
Windows ClangCL Shared Debug	1m 58s
Windows ClangCL Static Release	1m 58s
Windows ClangCL Static Debug	1m 51s
Windows Clang Shared Release	1m 46s
Windows Clang Shared Debug	56s
Windows Clang Static Release	2m 3s
Windows Clang Static Debug	1m 50s
Linux GCC Shared Release	55s
Linux GCC Shared Debug	52s
Linux GCC Static Release	1m 22s
Linux GCC Static Debug	58s
Linux Clang Shared Release	1m 3s
Linux Clang Shared Debug	35s
Linux Clang Static Release	1m 12s
Linux Clang Static Debug	1m 4s
macOS Clang Shared Release	1m 22s
macOS Clang Shared Debug	1m 29s
macOS Clang Static Release	1m 24s
macOS Clang Static Debug	1m 33s
	33m 56s

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