This adapts the Tobira details component from series details
to be usable in both series and event context.

Note that an Opencast patch (todo: link that patch)
is necessary for this to work.

This was requested by Bern. It is still possible to select
and deselect the path by clicking it's name, but next to that
a checkbox was added for visual clarity.

The checkbox is only shown when the path can be selected
(the page needs to be empty).

This factors out some code and applies some (yet non-inforced)
linting rules, ES6 syntax and formatting to limit some indentation
levels and improve readability.

Another feature requested by Bern, this adds the necessary
API and UI functions/components to edit existing series paths.

Editing is only allowed if the page with that path has no
other blocks than that of the series.

This pulls the code into a component to limit duplication.
The component can be used when "cancel" and "save" buttons
are needed in modal tabs that allow editing things like
access policies.

This makes it easier to reuse and limits duplicated code.

Most notably the series title (in Tobira context)
was made optional, so we don't have to pass an empty
string to Tobira when it's not specified.

This came up and was suggested in the technical meeting.
It does however mean that the Tobira tab will not really
follow the examplary design-"principles" of the other tabs.

Previously I had them hidden if they couldn't be checked.
After some feedback from Bern we decided to show them anyway, but
add a tooltip to explain why they can't be checked. The disabled
style isn't really that striking or self explanatory.
I hope this will prevent at least some confusion.

503 errors mean that Tobira either isn't configured, or not
configured correcty in Opencast. Unfortunately, it doesn't
distinguish between the two.
Since it might very well be the former, I think we shouldn't
show the error as a notification in the UI.
Instead there will be an info in console saying "Tobira isn't
configured (correctly)" and the Tobira tab will be hidden.
This solution isn't optimal but I think it's the best we
can do for now.

The other errors (404, 500) will trigger notifications that
are shown in the respective Tobira tab.