AAPT: Fix feature split generation of ID resources

ID resources that get generated on demand with the
notation @+id/name were previously not given the
appropriate type ID offset when being built as feature
splits.

This change declares an ID type ahead of time so that
the type ID offset is applied before IDs can be generated.

Bug:30607637
Change-Id: I122a9133cb01b35e9892103ec52fc228dc65bf1a