Add custom protocol button for mock samples

[255kb]

Is your feature request related to a problem? Please describe.
For the next release, when mockoon/mockoon#551 is finished, we should add a button on each mock sample to launch the mock in mockoon, using the custom protocol mockoon://

Describe the solution you'd like
Adding a new button
Linking to GitHub JSON files should use the following github domain: raw.githubusercontent.com