llvm20 linting fixes, containerize linux builds #144

Job	Run time
build-windows (clang-ue3-x86-release)	2m 41s
build-windows (clang-ue4-x64-release)	2m 32s
build-windows (msvc-ue3-x86-release)	1m 23s
build-windows (msvc-ue4-x64-release)	1m 25s
build-ubuntu (llvm-mingw-ue3-x86-release, llvm-mingw)	1m 33s
build-ubuntu (clang-cross-ue4-x64-release, clang-cross)	2m 52s
clang-tidy (clang-ue4-x64-release)	9m 59s
build-ubuntu (mingw-ue4-x64-release, mingw)	1m 42s
build-ubuntu (clang-cross-ue3-x86-release, clang-cross)	2m 45s
clang-tidy (clang-ue3-x86-release)	9m 18s
build-ubuntu (llvm-mingw-ue4-x64-release, llvm-mingw)	1m 46s
build-ubuntu (mingw-ue3-x86-release, mingw)	1m 32s
spelling	5s
clang-format	15s
	39m 48s

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