feat(encoding): add impls for `Encode*Value` #729

Job	Run time
Check	1m 32s
Check rustdoc intra-doc links	22s
Cross compile (armv7-unknown-linux-gnueabihf)	11s
Clippy	1m 10s
Cross compile (powerpc-unknown-linux-gnu)	10s
Rustfmt	13s
Cross compile (powerpc64-unknown-linux-gnu)	12s
Test Suite	1m 28s
Cross compile (wasm32-unknown-unknown)	9s
	5m 27s

Provide feedback