deposit: title from arXiv and from doi handling

* arXiv titles go into 245__a and 246__a.

* Title from DOI overwrites 245.

* Adds title_arXiv field mapping.

* Refactors import data when stripping arxiv id and doi prefixes.

Signed-off-by: Pedro Gaudêncio <pedro.gaudencio@cern.ch>