Generate storage info for pallet babe (#9760)

* Adding MaxEncodedLen for:
* NextConfigDescriptor
* AllowedSlots
* BabeEpochConfiguration

In prepation for adding storage information on pallet babe

* Adding stotage_info to pallet babe

Refactored UNDER_CONSTRUCTION_SEGMENT_LENGTH to become a runtime
parameter MaxSegmentLength

* Reinstate Slice as opposed to Vec

* Refactoring code to make it neater

* Replace `MaxSegmentLength` by
`UNDER_CONSTRUCTION_SEGMENT_LENGTH`
Stop exposing the bounds to the runtime

* Removing extra line

Co-authored-by: thiolliere <gui.thiolliere@gmail.com>

substrate/frame/babe/src/mock.rs

@@ -230,6 +230,8 @@ parameter_types! {
 	pub const ExpectedBlockTime: u64 = 1;
 	pub const ReportLongevity: u64 =
 		BondingDuration::get() as u64 * SessionsPerEra::get() as u64 * EpochDuration::get();
+	pub const MaxAuthorities: u32 = 10;
+	pub const MaxSegmentLength: u32 = 256;
 }
 
 impl Config for Test {
@@ -252,6 +254,7 @@ impl Config for Test {
 		super::EquivocationHandler<Self::KeyOwnerIdentification, Offences, ReportLongevity>;
 
 	type WeightInfo = ();
+	type MaxAuthorities = MaxAuthorities;
 }
 
 pub fn go_to_block(n: u64, s: u64) {