Add freinet agency information

[ztefanie]

For this feature #1751
To be able to push data to freinet (application/card data) we need an agencyId and accessKey
We have an api from freinet where we can fetch this information and map it via the regionIdentifiers (ars) to our regions

• Fetch the freinet agencyId and accessKey in regular cycles and the maybe (or not) save them to our system. Evaluate if caching is enough or not. Updates in the freinet system are possible and need to lead to updates in our system, e.g. if a region is added to freinet.
• show the agencyId and the accessKey in the region settings if they are available

[f1sh1918]

Since we need the agencyId for mapping accepting stores and for pushing data application data to freinet i think it makes sense to call the freinet api on backend start and store the agencyId in the regions table
This id will not change frequently, so i think on release to refetch it, it should be enough

[f1sh1918]

@ztefanie can you explain what bullet point 2 and 3 mean?
I think we just fetch this ids and i see no point in adding them manually?
Or do you mean if we cannot find any match?

[ztefanie]

yes, i think the idea was to map the freinet region ids with the eak region id's manually. But sure, if this can be done automatically, it is even better.

[f1sh1918]

Currently there are lots of wrong ars numbers so we can only map 40 regions, so far. I contacted freinet to check that.
In total we only get 50 regions out of 93 which is not sufficient :/

Since this xml won't change frequently i would rather hardcode the xml file from the api and read that instead of fetching it on every start.
agencyIds and ars shouldn't change.