chainHead: Add support for storage closest merkle descendant #14818 (#1153)

This PR adds support for fetching the closest merkle value of some key.


Builds on top of
- https://github.com/paritytech/trie/pull/199

Migrates https://github.com/paritytech/substrate/pull/14818 to the
monorepo.
Closes: https://github.com/paritytech/substrate/issues/14550
Closes: https://github.com/paritytech/polkadot-sdk/issues/1506

// @paritytech/subxt-team

---------

Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>
Co-authored-by: Sebastian Kunert <skunert49@gmail.com>

substrate/client/api/Cargo.toml

@@ -35,6 +35,7 @@ sp-runtime = { path = "../../primitives/runtime", default-features = false}
 sp-state-machine = { path = "../../primitives/state-machine" }
 sp-statement-store = { path = "../../primitives/statement-store" }
 sp-storage = { path = "../../primitives/storage" }
+sp-trie = { path = "../../primitives/trie" }
 
 [dev-dependencies]
 thiserror = "1.0.48"