fdo#69051 fdo#72028 PDF Import: text fixes

1. Set font size not only on text span, but also on text frame.
2. Some copy-paste from Draw import code to Writer import code:
2.1. Set frame's auto-size properties.
2.2. Set correctly line joins and caps.

Change-Id: I6beecfb50aa7f45d20cc3cb3740e415172394638
Reviewed-on: https://gerrit.libreoffice.org/9091
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>