fix: importer failing hard on page ref when
page name has same name as a task. Importer failed because of invalid
refs coming from gp-block/with-page-refs-and-tags which were caused
by get-first-page-by-title returning blocks. In 4f368d5c791d70fb2ae3ff59bc046fb98561d54f,
get-first-page-by-title started returning blocks instead of only pages
so this was undone. Fixes part of logseq/db-test#191