[FEATURE] Configure allowed pagetypes for indexing page records

The indexable page types are now hardcoded into the
Indexing Queue (function isAllowedPageType).

It's possible to configure with
plugin.tx_solr.index.allowedPageTypes = 1,7

Resolves: #34406
Change-Id: Ibee9a9fcde64665ad7f091a293d352769cf91291
Reviewed-on: https://review.typo3.org/25571
Reviewed-by: Hans Höchtl
Tested-by: Hans Höchtl