Create a new dto encapsulating mapping and similaritites and refactor functions

[tiadams]

• get_closest_mappings_with_similarities should be merged with get_closest_mappings and use the dto as response per default
• get_terminology_and_model_specific_closest_mappings_with_similarities should be merged with get_closest_mappings
• get_terminology_and_model_specific_closest_mappings can be removed

function signature should be as follows:

class MappingVectorMatch:

     mapping: Mapping
     similarity: Float

def get_closest_mappings(self, embedding_model_name, terminology_name=None, embedding, limit=5) -> List[MappingVectorMatch]:
    mapping_matches = []
    if terminology is None:
    # per default search over all terminologies
    else:
    # do terminology specific search
    return mapping_matches

[tiadams]

terminology_name should support types:

• None -> search over all terminologies
• String -> search for single terminology
• [String] -> search for several terminologies

[tiadams]

Makes sense to solve #21 before this to already use the new model class