Add convenience functions {,Must}Bech32ifyAddressBytes

[alessio]

Per @jackzampolin's request.

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[alexanderbez]

Fix lint/CI, otherwise LGTM 👍

[alessio]

@alexanderbez last build was OK. golangci-lint seems happy too. The only failing job is proto

Fix all linter warnings. Build was fine except proto, which is unrelated. See my comment above #5581 (comment)