Based on https://github.com/paritytech/polkadot-sdk/pull/3331
Related to https://github.com/paritytech/polkadot-sdk/issues/3268

Implements migrations with customizable block number to relay height
number translation function.

Adds block to relay height migration code for rococo and westend.

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