refs #19603 [finc] refactor getFincId and getAlternativeItemId

* allow list of ids and load results as batch from solr
* escape colons centralized in getFincId
* code styles
* move searchRelatedRecords from SolrMarcFincTrait to new finc\Controller\CustomTraits\SearchTrait
* call searchRelatedRecords instead of getFincId within getAlternativeItemId
* merge elements of getFincId into getAlternativeItemId
** handle multiple ids within getAlternativeItemId
** escape colon when existing
** rude exception catching
* replace call of getFincId by getAlternativeItemId within mapPaiaItems

co-authored by "Dorian Merz <merz@ub.uni-leipzig.de>"
* slight refactoring
* add more method comments

co-authored by "André Lahmann <lahmann@ub.uni-leipzig.de>"
* added comment for choice of trait location