Dynamic and remote configuration of provided SOS endpoints

[nuest]

The API is capable of providing access to different data sources, e.g. database or SOS services. For applications where a list of SOS services is dynamic, it would be useful to

• be able to change the list of available services at runtime, which requires updating of caches etc.
• provide a remote list of SOS endpoints to include, e.g. from a catalogue query

@ridoo Not sure what is possible already, feel free to directly edit this text!

Change SOS URLs at runtime

• Re-load the existing configuration file at a fixed interval
  • can include to request URLs from a remote location at a fixed interval
• Re-load the existing configuration file on file change with a file watcher (immediate or at a fixed interval)
• If this happens with an API endpoint (e.g. PUT ../service), then we need authentication.

Load SOS URLs from remote location

• send a requests to a remote server, e.g. a catalogue search, at startup of the component
• extract SOS endpoints from the response, e.g. XPath expressions, or regex
• update the TS-API cache