Use serde to encode/decode various TOML formats #882

Job	Run time
build-linux-pr (dev, x86_64-unknown-linux-gnu)	9m 49s
build-windows-pr (dev, x86_64-pc-windows-msvc)	9m 40s
build-linux-pr (dev, armv7-unknown-linux-gnueabihf)	3m 1s
build-windows-pr (dev, aarch64-pc-windows-msvc)	3m 20s
build-linux-pr (dev, aarch64-linux-android)	59s
build-linux-stable	0s
build-windows-pr (dev, x86_64-pc-windows-gnu)	3m 16s
build-linux-master	0s
build-linux-pr (release, x86_64-unknown-linux-gnu)	4m 50s
build-windows-pr (release, x86_64-pc-windows-msvc)	6m 5s
build-linux-pr (release, armv7-unknown-linux-gnueabihf)	4m 9s
build-windows-pr (release, aarch64-pc-windows-msvc)	5m 39s
build-windows-master	0s
build-linux-pr (release, aarch64-linux-android)	3m 47s
build-windows-pr (release, x86_64-pc-windows-gnu)	5m 3s
build-windows-stable	0s
build-all-features (x86_64-unknown-linux-gnu)	6m 0s
build-freebsd-master	0s
build-freebsd-stable	0s
build-macos-aarch64 (dev, aarch64-apple-darwin)	12m 22s
build-macos-x86_64 (dev, x86_64-apple-darwin)	15m 42s
check	45s
build-macos-aarch64 (release, aarch64-apple-darwin)	3m 42s
build-macos-x86_64 (release, x86_64-apple-darwin)	5m 29s
doc	7s
conclusion	3s
	1h 43m 48s

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