frame: support for serde added (#14261)

* frame: support for serde added

- enabled `serde` features in dependent crates, no gate feature introduced, linker should do the job and strip unused code.

- frame::staking: added impl of `serde::Serialize, serde::Deserialize` for `enum Forcing`

- primitives::runtime: impl_opaque_keys macro provides `Serialize/Deserialize` impl if `serde` is enabled

- primitives::staking: added impl of `serde::Serialize`, `serde::Deserialize` for `enum StakerStatus`

* frame::support: serde for pallets' GenesisConfig enabled in no-std

* Cargo.lock updated

* Update primitives/staking/Cargo.toml

Co-authored-by: Bastian Köcher <git@kchr.de>

* fix

* Cargo.lock update + missed serde/std in beefy

---------

Co-authored-by: Bastian Köcher <git@kchr.de>

substrate/primitives/runtime/src/traits.rs

@@ -1772,7 +1772,7 @@ macro_rules! impl_opaque_keys_inner {
 /// }
 /// ```
 #[macro_export]
-#[cfg(feature = "std")]
+#[cfg(any(feature = "serde", feature = "std"))]
 macro_rules! impl_opaque_keys {
 	{
 		$( #[ $attr:meta ] )*
@@ -1802,7 +1802,7 @@ macro_rules! impl_opaque_keys {
 }
 
 #[macro_export]
-#[cfg(not(feature = "std"))]
+#[cfg(all(not(feature = "std"), not(feature = "serde")))]
 #[doc(hidden)]
 macro_rules! impl_opaque_keys {
 	{