CLI for the light client

[romac]

Description

Implement a simple CLI for the light client, to verify headers up to a given height, perform attack detection, and report the evidence (if any) to primary and witness nodes.

Definition of "done"

A CLI for the light client can be invoked with the following interface:

Usage: tendermint-light-client-cli [OPTIONS] --chain-id <CHAIN_ID> --primary <PRIMARY> --witnesses <WITNESSES> --trusted-height <TRUSTED_HEIGHT> --trusted-hash <TRUSTED_HASH>

Options:
      --chain-id <CHAIN_ID>
          Identifier of the chain
      --primary <PRIMARY>
          Primary RPC address
      --witnesses <WITNESSES>
          Comma-separated list of witnesses RPC addresses
      --trusted-height <TRUSTED_HEIGHT>
          Height of trusted header
      --trusted-hash <TRUSTED_HASH>
          Hash of trusted header
      --height <HEIGHT>
          Height of the header to verify
      --trust-threshold <TRUST_THRESHOLD>
          Trust threshold [default: 2/3]
      --trusting-period <TRUSTING_PERIOD>
          Trusting period, in seconds (default: two weeks) [default: 1209600]
      --max-clock-drift <MAX_CLOCK_DRIFT>
          Maximum clock drift, in seconds [default: 5]
      --max-block-lag <MAX_BLOCK_LAG>
          Maximum block lag, in seconds [default: 5]
  -v, --verbose...
          Increase verbosity, can be repeated up to 2 times
  -h, --help
          Print help
  -V, --version
          Print version