Add available API methods for experiment types to DBpedia Sportlight

### Descritpion

GERBIL comes with a general DBpedia spotlight annotator used for the `OKE_Task1` experiment type (see https://github.com/dice-group/gerbil/blob/master/src/main/properties/annotators.properties#L47). However, the API states that it offers two additional methods https://www.dbpedia-spotlight.org/api which we should use.

### Solution
Add additional adapters for DBpedia Spotlight based on the methods that are offered by the API. From a quick view on the documentation, I would suggest the following mapping:
* `/annotate` comprises spotting, candidate mapping, disambiguation and linking = `OKE_Task1` (the currently used method)
* `/spot` comprises only spotting = `ERec` (:warning: should be checked)
* `/candidates` comprises spotting and candidate mapping = unclear whether it fits to one of our experiment types :warning:

Start with the DBpedia Spotlight annotator entry in src/main/properties/annotators.properties and compare the documented /annotate, /spot, and /candidates methods in the DBpedia Spotlight API. Determine whether /spot maps to ERec and whether /candidates matches an experiment type, then add the corresponding adapters and configuration for the supported mappings.

Written by the indexing model from the issue text.