Treating nav files as pages breaks querying content catalog

The fix for fe1ebbaf changes the family for nav files to 'page'. This breaks the ability to query the content catalog, as done in @djencks/asciidoctor-antora-indexer, as nav files are now returned from queries. This results in false broken links, as you can't link to a nav file. For instance the camel website now reports, from xref validation,

Unresolved xrefs (grouped by origin):

repo: https://github.com/apache/camel.git | branch: camel-2.x | component: components | version: 2.x
  path: docs/components/modules/dataformats/pages/index.adoc | xref: 2.x@components:dataformats:nav.adoc
  path: docs/components/modules/languages/pages/index.adoc | xref: 2.x@components:languages:nav.adoc
  path: docs/components/modules/others/pages/index.adoc | xref: 2.x@components:others:nav.adoc
  path: docs/components/modules/ROOT/pages/index.adoc | xref: 2.x@components:ROOT:nav.adoc

repo: https://github.com/apache/camel.git | branch: camel-3.4.x | component: components | version: 3.4.x
  path: docs/components/modules/dataformats/pages/index.adoc | xref: 3.4.x@components:dataformats:nav.adoc
  path: docs/components/modules/languages/pages/index.adoc | xref: 3.4.x@components:languages:nav.adoc
  path: docs/components/modules/others/pages/index.adoc | xref: 3.4.x@components:others:nav.adoc
  path: docs/components/modules/ROOT/pages/index.adoc | xref: 3.4.x@components:ROOT:nav.adoc

repo: https://github.com/apache/camel.git | branch: master | component: components | version: latest
  path: docs/components/modules/dataformats/pages/index.adoc | xref: latest@components:dataformats:nav.adoc
  path: docs/components/modules/languages/pages/index.adoc | xref: latest@components:languages:nav.adoc
  path: docs/components/modules/others/pages/index.adoc | xref: latest@components:others:nav.adoc
  path: docs/components/modules/ROOT/pages/index.adoc | xref: latest@components:ROOT:nav.adoc

antora: xref validation failed! Found 12 unresolved xrefs. See previous report for details.