Fix the cors issues

[MichaelsJP]

it was previously not possible to read in list of strings from the
config file.
This can now be done in a generic way.### Pull Request Checklist

• 1. I have rebased the latest version of the master branch into my feature branch and all conflicts
  have been resolved.
• 2. I have added information about the change/addition to functionality to the CHANGELOG.md file under the
  [Unreleased] heading.
• 3. I have documented my code using JDocs tags.
• 4. I have removed unnecessary commented out code, imports and System.out.println statements.
• 5. I have written JUnit tests for any new methods/classes and ensured that they pass.
• 6. I have created API tests for any new functionality exposed to the API.
• 7. If changes/additions are made to the ors-config.json file, I have added these to the ors config documentation
  along with a short description of what it is for, and documented this in the Pull Request (below).
• 8. I have built graphs with my code of the Heidelberg.osm.gz file and run the api-tests with all test passing
• 9. I have referenced the Issue Number in the Pull Request (if the changes were from an issue).
• 10. For new features or changes involving building of graphs, I have tested on a larger dataset
  (at least Germany), and the graphs build without problems (i.e. no out-of-memory errors).
• 11. For new features or changes involving the graphbuilding process (i.e. changing encoders, updating the
  importer etc.), I have generated longer distance routes for the affected profiles with different options
  (avoid features, max weight etc.) and compared these with the routes of the same parameters and start/end
  points generated from the current live ORS.
  If there are differences then the reasoning for these MUST be documented in the pull request.
• 12. I have written in the Pull Request information about the changes made including their intended usage
  and why the change was needed.
• 13. For changes touching the API documentation, I have tested that the API playground renders correctly.

Fixes #1394

Information about the changes

• Key functionality added: Correct CORS handling and configuration
• Reason for change: Currently, CORS cannot be handled correctly from the backend.

Examples and reasons for differences between live ORS routes, and those generated from this pull request

Required changes to ors config (if applicable)

"api_settings": {
      "cors": {
        "allowed": {
          "origins": [
			"*",
            "https://example.org"
          ],
          "methods": [
            "GET",
            "POST",
            "OPTIONS"
          ],
          "headers": [
            "Content-Type",
            "X-Requested-With",
            "accept",
            "Origin",
            "Access-Control-Request-Method",
            "Access-Control-Request-Headers",
            "Authorization"
          ]
        },
        "exposed": {
          "headers": [
            "Access-Control-Allow-Origin", "Access-Control-Allow-Credentials"
          ]
        },
        "preflight_max_age": 600
      }
    },

[MichaelsJP]

@TheGreatRefrigerator Should we put some default values for the CORS settings?
Many users will use their old config and still have problems. We could avoid that by settings a wildcard by default?

[TheGreatRefrigerator]

@TheGreatRefrigerator Should we put some default values for the CORS settings? Many users will use their old config and still have problems. We could avoid that by settings a wildcard by default?

Yes, the default values should mirror those we set in the sample config i guess.

[TheGreatRefrigerator]

Did some squashing and dropped the @CrossOrigin parts as they were overwriting the main CORS config, and resulted in further CORS Errors when pairing with the map clients.
Let's see if the new tests run through.

[takb]

LGTM. Checked locally, seems to work both in docker and run directly.