Merge branch 'w2p-46063_truncation-implementation' into w2p-46063_truncation-implementation-test-fixes

Conflicts:
	src/app/shared/object-grid/search-result-grid-element/community-search-result/community-search-result-grid-element.component.spec.ts

Fix pagination issue on change page size

Conflicts:
	src/app/object-list/item-list-element/item-list-element.component.ts
	src/app/object-list/search-result-list-element/item-search-result/item-search-result-list-element.component.scss
	src/app/shared/object-list/search-result-list-element/item-search-result/item-search-result-list-element.component.ts
	src/styles/_custom_variables.scss
	src/styles/_mixins.scss

Store requests by UUID instead of URL

fixed an issue where certain GET requests would be performed more often then needed and added tests for the requestservice (not everything tested yet)

Replaced Http with HttpClient

Closes #150 

Switched to storing requests based on UUID, generalized UUIDIndexReducer to work with any type of index