Remove OpenCV and add STB #2351

Job	Run time
python-lint	49m 6s
clang-format	1s
ubuntu-clang-build	1s
macos-clang-build	1s
windows-msvc-build	1s
windows-clang-build	1s
ubuntu-gcc-build	1s
ubuntu-gcc-test	1s
ubuntu-clang-sanitizer-build	1s
ubuntu-clang-test	1s
windows-clang-test	1s
macos-clang-test	1s
ubuntu-clang-sanitizer-test	1s
windows-msvc-test	1s
windows-clang-test-extended	1s
ubuntu-clang-test-extended	1s
macos-clang-test-extended	1s
ubuntu-gcc-test-extended	1s
windows-msvc-test-extended	1s
ubuntu-clang-sanitizer-test-extended	1s
ubuntu-gcc-build-codecov	1s
ubuntu-gcc-build-perf-stats	1s
	49m 27s

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