Add a headless app mode

[joaquimrocha]

Current situation Our desktop apps use Electron to run the UI and package it like a desktop app. However, this means that the user cannot use their favorite browser and browser features (like bookmarks, groups, etc.).

Ideal future situation There is a way to run Headlamp's destop version using the default browser.

Implementation options

• All apps have a headless mode, which means that when they are run with this option, they will open the default browser instead of using the electron view.
• We build a new headlamp-headless version of the desktop app which doesn't include Electron (meaning the app is also lighter in size).

[ashu8912]

This has landed in the master branch. We can close this issue now.

[ashu8912]

@joaquimrocha