accounts, cmd, eth, internal, mobile, node: split account backends

accounts/abi/bind/auth.go

accounts/accounts.go

accounts/backend.go

accounts/errors.go

accounts/keystore/address_cache.go

accounts/keystore/address_cache_test.go

accounts/keystore/key.go

accounts/keystore/keystore.go

accounts/keystore/keystore_passphrase.go

accounts/keystore/keystore_passphrase_test.go

accounts/keystore/keystore_plain.go

accounts/keystore/keystore_plain_test.go

accounts/keystore/keystore_test.go

accounts/keystore/presale.go

accounts/keystore/testdata/dupes/1

accounts/keystore/testdata/dupes/2

accounts/keystore/testdata/dupes/foo

accounts/keystore/testdata/keystore/.hiddenfile

accounts/keystore/testdata/keystore/README

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