Node/P2P: Add default bootstrap peers

[bruce-riley]

This PR hard codes the bootstrap peers and network ID for the guardian, spy and query proxy server, based on the environment (mainnet or testnet). It allows them to be overridden using the existing parameters, but that should be discouraged.

For devnet / tilt, the existing parameters should still be used because the bootstrap peer may not be deterministic.

The following config parameters should be removed for guardiand and the query proxy server:

• --network
• --bootstrap
• --ccqP2pBootstrap

The following config changes should be made for the spy:

• Add --env with a value of mainnet or testnet.
• Remove --network
• Remove --bootstrap

Scenarios Tested

• Spy in tilt (devnet)
• Spy with --env mainnet
• Spy with --env testnet
• Spy with no --env but network parameters (allowed)
• Spy with both --env and network parameters (not allowed)
• CCQ server in tilt (devnet)
• CCQ server with --env mainnet
• CCQ server with --env testnet
• Guardian in tilt (devnet)
• Guardian in testnet, no network parameters (allowed)
• Guardian in testnet, with network parameters (allowed)
• Guardian in mainnet, no network parameters (allowed)
• Guardian in mainnet, with network parameters (allowed)

[evan-gray]

seems reasonable to me. relatively small amount of code for less config needed across the ecosystem.