Refactored enums to lowercase, refactored adv. search

...c/main/java/at/tuwien/entities/identifier/Identifier.java

.../at/tuwien/entities/identifier/IdentifierDescription.java

.../java/at/tuwien/entities/identifier/IdentifierFunder.java

...a/at/tuwien/entities/identifier/IdentifierFunderType.java

...in/java/at/tuwien/entities/identifier/IdentifierType.java

.../tuwien/entities/identifier/NameIdentifierSchemeType.java

...java/at/tuwien/entities/identifier/RelatedIdentifier.java

...in/java/at/tuwien/entities/identifier/VisibilityType.java

...in/java/at/tuwien/entities/maintenance/BannerMessage.java

...at/tuwien/converters/IdentifierTypeConverterUnitTest.java

...ervices/src/main/java/at/tuwien/config/JacksonConfig.java

...ervices/src/main/java/at/tuwien/config/JacksonConfig.java

dbrepo-search-service/app/api/routes.py

dbrepo-search-service/app/opensearch_client.py

dbrepo-ui/api/advanced_search.service.js

dbrepo-ui/api/search.service.js

dbrepo-ui/components/dialogs/Semantics.vue

dbrepo-ui/layouts/default.vue

dbrepo-ui/pages/search/index.vue