* Replace hardcoded sent ether label on confirm screen
* replace transaction type SENT_ETHER with network agnostic SENDING_NATIVE_ASSET
* remove sentEther translation base
* make backwards compatible with lingering transaction of legacy sentEther type
* update localalization files
* fixup legacy sentEther transaction type
* changing new transaction type away from localization string
* revert migration tests
* update fixtures and test data
* update name of new transaction type
* add migration
* remove legacy SENT_ETHER from transaction types enum object
If the initial network when the extension is started is something other
than Mainnet, the swaps controller will never successfully retrieve
swap quotes. This is because the `ethers` provider used by the swaps
controller doesn't allow network changes by default - it assumes that
the network remains the same as when the provider was initialized.
This was fixed by hard-coding Mainnet as the initial chain ID for this
`ethers` provider used by the swaps controller.
Some adjustments needed to be made to the `provider` stub to allow
setting `1` as the network ID and chain ID in unit tests.
