Ensure data size of identity pallet is bounded (#9168)

* Ensure data size of identity pallet is bounded

* Fix unit tests for identity pallet

* Move identity pallet custom types into its own module

* Make use of NoBound family traits

* Fix identity pallet benchmarks

* Enumerate type imports

* Properly convert to BoundedVec in benchmarks

* Re-export types

* Use BoundedVec when storing sub identities

* Add generate_storage_info

* Manually implement MaxEncodedLen on select types

* Use ConstU32 instead of parameter_type

* Leverage DefaultNoBound and add some comments

* Use max_encoded_len() instead of hardcoded constant

* Use MaxEncodedLen in parity-scal-codec

* Add get_mut method for WeakBoundedVec

* Use expect on an infallible operation

* Rewrite as for loop

substrate/frame/support/src/storage/bounded_vec.rs

@@ -122,6 +122,14 @@ impl<T, S> BoundedVec<T, S> {
 	pub fn retain<F: FnMut(&T) -> bool>(&mut self, f: F) {
 		self.0.retain(f)
 	}
+
+	/// Exactly the same semantics as [`Vec::get_mut`].
+	pub fn get_mut<I: SliceIndex<[T]>>(
+		&mut self,
+		index: I,
+	) -> Option<&mut <I as SliceIndex<[T]>>::Output> {
+		self.0.get_mut(index)
+	}
 }
 
 impl<T, S: Get<u32>> From<BoundedVec<T, S>> for Vec<T> {