Implement `CheckMetadataHash` extension (#4274)

This implements the `CheckMetadataHash` extension as described in
[RFC78](https://polkadot-fellows.github.io/RFCs/approved/0078-merkleized-metadata.html).

Besides the signed extension, the `substrate-wasm-builder` is extended
to support generating the metadata-hash.

Closes: https://github.com/paritytech/polkadot-sdk/issues/291



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Co-authored-by: Oliver Tale-Yazdi <[email protected]>
Co-authored-by: joe petrowski <[email protected]>
Co-authored-by: Liam Aharon <[email protected]>
Co-authored-by: Kian Paimani <[email protected]>