Merkle Mountain Range pallet (#7312)

* Add MMR pallet.

* WiP

* Working on testing.

* WiP - test

* Tests passing.

* Add proof generation.

* Generate and verify proofs.

* Allow verification of older proofs.

* Move stuff to a module.

* Split MMR stuff to it's own module.

* Add docs.

* Make parent hash optional.

* LeafData failed approach.

* Finally implement Compact stuff.

* Compact encoding WiP

* Implement remaining pieces.

* Fix tests

* Add docs to compact.

* Implement for tuples.

* Fix documentation.

* Fix warnings and address review suggestion.

* Update frame/merkle-mountain-range/src/primitives.rs

Co-authored-by: cheme <[email protected]>

* Address review grumbles.

* Removing missing crate.

* Fix test.

* Add some docs and test.

* Add multiple instances.

* Cargo.toml sync.

* Fix no_std compilation.

* More no_std stuff.

* Rename MMR struct.

* Addressing other grumbles.

* Fix test.

* Remove format for no_std compat.

* Add test for MMR pallet.

* Fix std feature.

* Update versions.

* Add to node/runtime.

* Add hook to insert digest.

* Make primitives public.

* Update lib.rs

tech spec/typos etc

* Use WeightInfo and benchmarks.

* Fix test.

* Fix benchmarks.

* Trait -> Config.

* Fix typo.

* Fix tests.

Co-authored-by: cheme <[email protected]>
Co-authored-by: Addie Wagenknecht <[email protected]>