Remove unnecessary dependencies for bitcoin-cli

This commit removes all the unnecessary dependencies (key, core, netbase,
sync, ...) from bitcoin-cli.

To do this:
- Shards the chain parameters into BaseParams, which contains just the
  RPC port and data directory (as used by utils and bitcoin-cli) and
  Params, with the rest.
- The network time-offset-related functions from util.cpp are split into
  timedata.(cpp|h).