v5.5.1

Changes:

• Added hdLedger to util-crypto for Ledger-compatible bip32+ed25519 derivation
• Added hmac{Sha256, 512} to util-crypto
• Add slip44 indices for Ledger into @polkadot/networks
• Remove module entry in package.json (only rely on exports map)
• Remove direct references to global object, use @polkadot/x-global
• Update @ledgerhq dependencies to latest