Repo search fixes and RepoDb FTS fixes

Backward-incompatible changes:

• Repo::getResourceById*() take acdhOeaw\arche\lib\SearchConfig instead of the string $className parameter. This allows controlling amount of metadata returned and makes their API more orthogonal with getResources*() methods (the returned resource class can be still set with the SearchConfig object).

Fixes:

• RepoDb::getFtsQuery() tuned for better highlighting of full text search queries matching identifier URIs