Fixes#788.
Fixes#853.
Fixes#856.
refactor: gas estimation and transaction sends have been abstracted to allow calling `estimateGas`, `send`, and `call` on the contract method (similar to the web3 API).
Moved sticker pack gas estimation and purchase tx over to the new API
*Sticker purchase:*
- gas estimate is done using new API and debounced using a timer
*Wallet send transaction:*
- tokens can now be sent
- gas is estimated correctly for a token tx, and debounced using a timer
***NOTE***
1. If attempting to send tokens on testnet, you must use a custom token as the token addresses in the pre-built list are for mainnet and will not work on testnet.
2. The new API should support all existing gas estimates, send txs, and calls. The loading of sticker pack data, balance, count, purchased sticker packs, etc, can be moved over to the new API. Almost all of the `eth_sendTransaction`, `eth_gasEstimate`, and `eth_call` could be move over as well (that's the idea at least).
Add gas estimate for sticker pack purchase.
Update transaction for sticker pack purchase.
Add GasValidator component which validates gas is selected correctly and displays an error message if not. This component is not visible until it is not valid (at which point the valdiation error message is displayed).
In a future PR, need to:
1. estimate gas for token txfer (sendTransaction) via a normalised method for estimating gas for EthSend
2. move sticker pack purchase to use an EthSend object so gas can be estimated and tx sent