Improve Test Suite

Right now, we have quite a few unit tests and some end-to-end tests for the launching process. We should aim to improve this and get a better coverage of the code.

## Unit Tests

We are aiming for one unit test file per file. The biggest issue with unit tests is the amount of mocking we need to do to make sure we don't have side-effects.

## E2E

We are using [Spectron](https://github.com/electron-userland/spectron) for our end-to-end tests and it can sometimes be limiting since we have a menubar application and Spectron **does not allow** to test menus.

Some interesting E2E tests that we should aim to make (if possible):

- Test menubar interaction.
- Test global shortcuts functionality.
- Test adding `ipfs` to `PATH`.
- Test Protocol Handlers (macOS and Windows only).