Feature: Support stlink v2 isol variant #1924

Job	Run time
build-mingw (windows-2022, ucrt64)	2m 34s
build-linux (ubuntu-20.04, focal, clang-15, 12.2.Rel1)	3m 30s
build-linux (ubuntu-20.04, focal, gcc-11, 12.2.Rel1)	3m 42s
build-mingw (windows-2022, clang64)	2m 32s
size-diff	45s
build-linux (focal, 96b_carbon)	43s
build-linux (focal, bluepill)	33s
build-linux (focal, f072)	35s
build-linux (focal, f3)	36s
build-linux (focal, f4discovery)	34s
build-linux (focal, hydrabus)	36s
build-linux (focal, launchpad-icdi)	33s
build-linux (focal, native)	32s
build-linux (focal, stlink)	37s
build-linux (focal, stlinkv3)	38s
build-linux (focal, swlink)	37s
	19m 37s

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