Performance check: add test for extraction of single page
Performance check: add test for extraction of single page

It is common to just read a few objects. Checking extraction of the
first page exercises this to make sure we don't accidentally introduce
a change that makes that case worse, such as adding an unnecessary
traversal of the file, prematurely resolving objects we don't need,
etc.

jberkenbilt/qpdf,jberkenbilt/qpdf,jberkenbilt/qpdf,qpdf/qpdf,qpdf/qpdf,qpdf/qpdf,jberkenbilt/qpdf,jberkenbilt/qpdf,qpdf/qpdf,qpdf/qpdf