Detect network EIP-1559 support; conditionally add `gasPrice`

[jtrein]

With our current updates to remove legacy tx support by removing the gasPrice field, and also updating our Web3 library, we have broken tx's for Trezor and Ledger wallets using MetaMask. This is expected behaviour, as stated by MetaMask, but we should detect EIP-1559 support and conditionally set the gasPrice field exactly as we used to if no EIP support was detected.

References:

• https://metamask.io/1559
• https://github.com/MetaMask/metamask-extension/blob/e6543a83effce673c22397f828f410dff74bace9/app/scripts/controllers/network/network.js#L163
• https://github.com/MetaMask/metamask-extension/pull/11722
• https://github.com/ChainSafe/web3.js/blob/a57dd3c5db0e4acb5b326714bd9a2d7ada00c2dc/packages/web3-core-method/src/index.js#L773