Step in https://github.com/paritytech/polkadot-sdk/issues/3268

This PR adds the ability for these pallets to specify their source of
the block number. This is useful when these pallets are migrated from
the relay chain to a parachain and vice versa.

This change is backwards compatible:
1. If the `BlockNumberProvider` continues to use the system pallet's
block number
2. When a pallet deployed on the relay chain is moved to a parachain,
but still uses the relay chain's block number

However, we would need migrations if the deployed pallets are upgraded
on an existing parachain, and the `BlockNumberProvider` uses the relay
chain block number.

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Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>