Add read-flash support #452

Job	Run time
Check lib (x86_64-unknown-linux-gnu)	31s
Check (x86_64-apple-darwin)	1m 6s
Check lib (aarch64-unknown-linux-gnu)	1m 9s
Check (x86_64-unknown-linux-gnu)	22s
Clippy (x86_64-unknown-linux-gnu)	28s
Check lib (armv7-unknown-linux-gnueabihf)	1m 19s
Check (x86_64-unknown-linux-musl)	35s
Clippy (aarch64-unknown-linux-gnu)	1m 31s
Check (x86_64-pc-windows-msvc)	3m 30s
Clippy (armv7-unknown-linux-gnueabihf)	1m 43s
Check MSRV (x86_64-unknown-linux-gnu)	32s
Check (aarch64-unknown-linux-gnu)	1m 27s
Check MSRV (aarch64-unknown-linux-gnu)	1m 35s
Check (armv7-unknown-linux-gnueabihf)	1m 27s
Check MSRV (armv7-unknown-linux-gnueabihf)	1m 42s
Rustfmt	17s
Unit Tests (x86_64-unknown-linux-gnu)	29s
Unit Tests (aarch64-unknown-linux-gnu)	1m 27s
Unit Tests (armv7-unknown-linux-gnueabihf)	1m 20s
	22m 30s

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