refactor: VVMマニフェストで`#[serde(flatten)]`を活用 #3208

Job	Run time
actionlint	11s
rust-lint	4m 17s
rust-unit-test	5m 49s
shellcheck	17s
validate-cargo-lock	22s
build-and-test-java-api (windows-latest)	6m 24s
build-and-test-java-api (macos-latest)	2m 41s
build-and-test-java-api (ubuntu-latest)	2m 41s
build-and-test-python-api (windows-latest)	5m 47s
build-and-test-python-api (macos-latest)	3m 20s
build-and-test-python-api (ubuntu-latest)	3m 8s
build-unix-cpp-example (macos-latest, osx-x64-cpu-cpp-shared)	1m 45s
build-windows-cpp-example	3m 35s
build-unix-cpp-example (ubuntu-latest, linux-x64-cpu-cpp-shared)	1m 34s
c-header	44s
rust-integration-test-strategy-matrix	1s
rust-integration-test (macos-13)	3m 49s
rust-integration-test (ubuntu-20.04)	2m 0s
	48m 25s

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