Make constants exposable in metadata (#2975)

* Some cleanup

* Add module constant metadata declaration

* Begin to integrate the constants in `decl_module`

* Fixes tests

* Fix compilation and add tests

* Remove duplicate code

* Expose constants in democracy and staking + further fixes

* Update srml/metadata/src/lib.rs

Co-Authored-By: YJ <yjkimjunior@gmail.com>

* Hide `RawEvent` metadata function

* Prevent whitespaces in types

* Fix `offchain_worker` and `constants` with instances

* Up the `impl_version`

* Fix macro

* Incrase impl_version

substrate/node/runtime/src/lib.rs

@@ -59,7 +59,7 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	impl_name: create_runtime_str!("substrate-node"),
 	authoring_version: 10,
 	spec_version: 99,
-	impl_version: 105,
+	impl_version: 106,
 	apis: RUNTIME_API_VERSIONS,
 };
 
@@ -176,6 +176,7 @@ parameter_types! {
 	pub const EnactmentPeriod: BlockNumber = 30 * 24 * 60 * MINUTES;
 	pub const CooloffPeriod: BlockNumber = 30 * 24 * 60 * MINUTES;
 }
+
 impl democracy::Trait for Runtime {
 	type Proposal = Call;
 	type Event = Event;