FileGDB: implement IgnoreFields API to speed-up a bit the conversion of a sub-set of fields when there's a huge amount of them (e.g. Tiger database).

git-svn-id: https://svn.osgeo.org/gdal/trunk@26163 f0d54148-0727-0410-94bb-9a71ac55c965
Merge branch 'trunk' of github.com:rouault/gdal into trunk_with_coverage