WIP - use craco in fether-react, and jest in fether-electron, as instructed, but tests still dont work

* Update tests to include missing `token` property to a Tx of Ether or Token

* Update tests to include missing `address` property to a Tx of Ether to fixes `TypeError: Cannot read property 'address' of undefined` error

* Update tests to include missing `options` and `args` properties to the Tx so the second argument passed to `transfer$` in `contractForToken(token.address).transfer$(..., ...)` is not NaN

* Fix error `ReferenceError: regeneratorRuntime is not defined`

Fixes error: 'pipelineOperator' requires 'proposal' option whose value should be one of: 'minimal', 'smart'

See https://github.com/sharegate/craco/issues/61.
Updating to craco 3.3.1 resolves error when trying to install dependencies and build:
```
Error: Cannot find module '~/code/src/paritytech/fether/node_modules/react-scripts/config/webpack.config.dev'
```

- Add option to import a Parity Signer account. It is then stored in
local storage.

- Send transactions with Parity Signer accounts

- Refactor sendStore so that "token" (and chainId) is inside this.tx;
avoids having to pass `token` around every function, and it makes sense
to put it in the object since it is part of the tx info.

- Add account type (either node or signer) to accountsInfo

- Add account type to withAccount; output props are now `{account:
{address, type}}` instead of `{accountAddress}`

move jsonbackup to its own component/route

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