common-packaging.post: better generation of .repo files

common-packaging.post: better generation of .repo files

Zypper repo files are now generated using the information
stored in /etc/tizen-build.conf.

This allows to generate 4 repo files with accurate information
whatever the profile, obs repository etc.:
- snapshot: corresponds to the current snapshot
- update: latest snapshot
- daily: latest daily release
- weekly: latest weekly release

Debug repositories are also defined in the same .repo files.

Change-Id: I0ea07d7383499529d74a764de0ec69e9333ae54f
Signed-off-by: Stephane Desneux <stephane.desneux@open.eurogiciel.org>