Move pushEvent inside MatomoElement, make sure event name is non-empty string and add extra handling for TypeError

This prevents eslint from traversing the parent directories. In
the case there was a conflicting eslint config in a parent directory it would
error out otherwise (like is the case in our apps)

See issue #33

See issue #33

Use "await JSONLD.getInstance()" instead

No longer needed

In theory this can replace all other API.

We can access that API without a token.

appending "#debug" to the URL enables it again. Not sure if this
the best mechanism, but better than spaming the console for now.

Pull out nextcloudfilepicker styles to file-handling styles, styling, translation and function of clipboard

Instead of handling the visibility checks at render time we keep around a list
of visible routes and emit an event when they change. This way the welcome activity
can mirror what the menu shows and update at the same time.