This moves the eth config definition into a separate package, eth/ethconfig.
Packages eth and les can now import this common package instead of
importing eth from les, reducing dependencies.
Co-authored-by: Felix Lange <fjl@twurst.com>
# Conflicts:
# cmd/faucet/faucet.go
# cmd/geth/config.go
# cmd/utils/cmd.go
# cmd/utils/flags.go
# cmd/utils/flags_legacy.go
# console/console_test.go
# eth/backend.go
# eth/bloombits.go
# eth/ethconfig/config.go
# ethclient/ethclient_test.go
# graphql/graphql_test.go
# les/api_test.go
# les/client.go
# les/commons.go
# les/costtracker.go
# les/server.go
# les/test_helper.go
# mobile/geth.go
