Develop Web3.js in feature parity with Solana

## Motivation
The Solana protocol uses [Feature Gates](https://github.com/solana-labs/solana/wiki/Feature-Gate-Activation-Schedule) to make consensus-breaking changes to the protocol. Often, these changes have downstream effects on Web3.js (examples: solana-labs/solana-web3.js#2013, solana-labs/solana-web3.js#2101).

It would benefit our development workflow greatly to have some semblance of feature parity with the Solana protocol, possibly by leveraging these feature IDs in Web3.js.

## Ideas
We could do this a number of ways:
- Introduce build steps for bootstrapping either a pre- or post- feature activation change in a client bundle.
- Rely on RPC calls to query feature status in order to control functionality (yuck).
- Leverage feature IDs and the [Feature Activation Schedule](https://github.com/solana-labs/solana/wiki/Feature-Gate-Activation-Schedule) to manage development branches and subsequent releases.

We should discuss further!