Add `AVInputFomat::find`, improve`AVFormatContextInput::open` (#116) #320

Job	Run time
rustfmt_check (macos-latest)	23s
rustfmt_check (windows-latest)	44s
rustfmt_check (ubuntu-latest)	10s
docs_rs_check	58s
rust_clippy_check_ubuntu	7m 42s
build_static_and_test_ubuntu (release/4.3, nightly, no valgrind)	8m 51s
build_static_and_test_ubuntu (release/4.3, 1.64.0, no valgrind)	9m 44s
build_static_and_test_ubuntu (release/5.0, nightly, no valgrind)	9m 24s
build_static_and_test_ubuntu (release/5.0, 1.64.0, no valgrind)	12m 5s
build_static_and_test_ubuntu (release/6.0, nightly, valgrind)	1h 37m 50s
build_static_and_test_ubuntu (release/6.0, nightly, no valgrind)	9m 32s
build_static_and_test_ubuntu (release/6.0, 1.64.0, no valgrind)	10m 11s
rust_clippy_check_windows	3m 31s
build_dynamic_and_test_windows_pre	10m 48s
build_dynamic_and_test_windows (nightly)	3m 57s
build_dynamic_and_test_windows (1.64.0)	4m 3s
	3h 9m 53s

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