Add an option to generate tests (by choosing a test library)

[gdarchen]

Is your feature request related to a problem? Please describe.
The CLI should probably propose an option enabling to create a test folder (maybe also enabling the choice of the test library ?) containing some basic tests. For instance, we could test that the generated component renders without crashing.

Describe the solution you'd like
We could, for example, imagine some --tests:jest argument to tell the CLI to also generate a tests/ folder aside the components one, containing a generated test file with the Jest library.

We should propose to select the library among an exhaustive list.

Describe alternatives you've considered
The only alternative I can imagine is to generate those tests by hand...

[tanohzana]

I'll do it