test: cleanup

[jordyvanderhaegen]

This PR refactors the current test-suite to be more up to date with recent standards.

• Use orchestra/testbench instead of orchestra/testbench-browser-kit. This was originally PR'd in Fix route translation for Laravel 5.4 #399 but can now be replaced with the core package.
• Route registration now utilizes the name method to assign route names, instead of the old array-syntax.
• Route registration is now more aligned with examples in the README.
• Changed the assertResponseOk with assertStatus(200), which improves readability.
• Swapped the order of some assertEquals parameters, as actual and expected were passed the wrong way around.

[jordyvanderhaegen]

@niels-numbers mind taking a look at this one? CI will still fail until #948 gets merged.
Ping me and I'll merge master after that's done.