fix: Fixes Cannot read getGlobal of undefined since remote must be enabled in fether-electron config to use fether-react

In the Babel 7 migration guide these are the different plugings and
to add them:

See https://babeljs.io/blog/2018/07/27/removing-babels-stage-presets#migrating

```
// Stage 0
"@babel/plugin-proposal-function-bind",

// Stage 1
"@babel/plugin-proposal-export-default-from",
"@babel/plugin-proposal-logical-assignment-operators",
["@babel/plugin-proposal-optional-chaining", { "loose": false }],
["@babel/plugin-proposal-pipeline-operator", { "proposal": "minimal" }],
["@babel/plugin-proposal-nullish-coalescing-operator", { "loose": false }],
"@babel/plugin-proposal-do-expressions",

// Stage 2
["@babel/plugin-proposal-decorators", { "legacy": true }],
"@babel/plugin-proposal-function-sent",
"@babel/plugin-proposal-export-namespace-from",
"@babel/plugin-proposal-numeric-separator",
"@babel/plugin-proposal-throw-expressions",

// Stage 3
"@babel/plugin-syntax-dynamic-import",
"@babel/plugin-syntax-import-meta",
["@babel/plugin-proposal-class-properties", { "loose": false }],
"@babel/plugin-proposal-json-strings"
```

Fixes errors:

```
{ Error: Cannot find module '@babel/plugin-proposal-class-properties' from '/Users/scon/code/src/paritytech/fether/packages/fether-ui'
```

```
Failed to minify the bundle. Error: static/js/main.f19a0eac.chunk.js from Terser
TypeError: Cannot read property 'minify' of undefined
```

See https://github.com/electron/electron/blob/master/docs/api/native-image.md#template-image

* 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 `SyntaxError ... Decorators transform is necessary.` (regarding use of `@observable`)
* Fixes `Decorating class property failed. Please ensure that proposal-class-properties is enabled and set to use loose mode. To use proposal-class-properties in spec mode with decorators, wait for the next major version of decorators in stage 2.`