Multithread ETH sync

[kajoseph]

NOTE: This PR will bump the minimum required node version from 8 to 10 for the use of worker threads.

This PR:

• Adds multi-threaded and multi-client syncing
• Introduces a GethRPC class. This is not a properly working class and thus has a throw in the constructor to prevent usage at this time. The full support for geth will be added in a subsequent PR
• Refactors Parity naming to Erigon
• Refactors some typings for consistency
• Updates a few miscellaneous things:
  • bitcore-node.service file to use typescript outdir
  • removes unused and outdated CHANGELOG.md
  • fixes Web3Proxy api endpoint and adds config value
  • updates karma deps in bitcore-build

TODOs:

• geth support
• DRY-ing up some code, specifically the processBlock functions in p2p.ts and syncWorker.ts

[kajoseph]

I merged in https://github.com/bitpay/bitcore/pull/3349 to ensure no merge conflicts. Since it and this will require Node version increases, and thus a major version bump, they should be merged into master at the same time.