Embed runtime version as a custom section (#8688)

* emit a custom section from impl_runtime_apis!

This change emits a custom section from the impl_runtime_apis! proc macro.

Each implemented API will result to emitting a link section `runtime_apis`.
During linking all sections with this name will be concatenated and
placed into the final wasm binary under the same name.

* Introduce `runtime_version` proc macro

This macro takes an existing `RuntimeVersion` const declaration, parses
it and emits the version information in form of a linking section.
Ultimately such a linking section will result into a custom wasm
section.

* Parse custom wasm section for runtime version

* Apply suggestions from code review

Co-authored-by: David <dvdplm@gmail.com>

* Fix sc-executor integration tests

* Nits

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Refactor apis section deserialization

* Fix version decoding

* Reuse uncompressed value for CallInWasm

* Log on decompression error

* Simplify if

* Reexport proc-macro from sp_version

* Merge ReadRuntimeVersionExt

* Export `read_embedded_version`

* Fix test

* Simplify searching for custom section

Co-authored-by: David <dvdplm@gmail.com>
Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

substrate/primitives/version/proc-macro/Cargo.toml

@@ -0,0 +1,26 @@
+[package]
+name = "sp-version-proc-macro"
+version = "3.0.0"
+authors = ["Parity Technologies <admin@parity.io>"]
+edition = "2018"
+license = "Apache-2.0"
+homepage = "https://substrate.dev"
+repository = "https://github.com/paritytech/substrate/"
+description = "Macro for defining a runtime version."
+documentation = "https://docs.rs/sp-api-proc-macro"
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
+
+[lib]
+proc-macro = true
+
+[dependencies]
+quote = "1.0.3"
+syn = { version = "1.0.58", features = ["full", "fold", "extra-traits", "visit"] }
+proc-macro2 = "1.0.6"
+proc-macro-crate = "1.0.0"
+codec = { package = "parity-scale-codec", version = "2.0.0", features = [ "derive" ] }
+
+[dev-dependencies]
+sp-version = { version = "3.0.0", path = ".." }