Make sure pallet versions are set at genesis (#7451)

* Make sure pallet versions are set at genesis

This pr ensures that pallet versions are also set at genesis. It does
this by hooking into the runtime `GenesisConfig` which means that it
will only work when the storage is setup using this genesis config. So,
the version will not be set in pallet local tests. However, I think this
isn't such a problem. The genesis config will call `on_genesis` on all
pallets. This function comes from the new trait `OnGenesis`. Currently
the user is not able to provide any custom implementation of this trait.

Besides that it also implements `Clone` and `Copy` for the pallet
version struct.

This pr also moves the macro for generating the runtime genesis config
to `frame-support` as most of the other FRAME related macros.

* Reduce line width

* Update frame/support/src/traits.rs

Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>

Co-authored-by: Alexander Popiak <alexander.popiak@parity.io>

substrate/frame/support/src/lib.rs

@@ -58,6 +58,8 @@ pub mod event;
 #[macro_use]
 pub mod metadata;
 #[macro_use]
+pub mod genesis_config;
+#[macro_use]
 pub mod inherent;
 #[macro_use]
 pub mod unsigned;