borg: manage more error codes and to improve the output

See merge request !70

Multiple improvements in borg handler

See merge request !69

replace borg source/ignore_missing by filter_warnings, and allow to disable warnings on file changed during backup

Quick fix for #11349 : Add support for generic options config value

See merge request !67

Allow setting additional parameters at borg invocation time

Inspired from the duplicity handler's options variable

Quick fix for #11349

For package installation, the runner $TMPDIR may not be big enough, eg
when rebuilding an initramfs it runs out of space, so use a new function
that sets it explicitly.

This file is a precious energy drain to keep up to date and duplicates
the Git history where everyone's contribution is now recorded.

Adding the port parameter to the borg handler with a default value of 22
is causing issues for users who had been using the standard ssh config
file to set the remote port, since the -p cli argument overrides the
configuration. This removes the default port number and only uses it in
the connection string if defined.

Add basic prometheus metrics for backup status.

See merge request !55

Packager email: Petr.Klima@madeta-group.cz no longer exists

See merge request !52

Fix #11328

Closes #11328

See merge request !61

fix borg example: set cache_directory to source section

See merge request !63

Actually run duplicity remove-older-than. Fix #11345

Closes #11345

See merge request !64

Actually run duplicity remove-older-than. Fix regression in f007227e

dup.helper: re-add a version of the do_dup_src function

Closes #11332

See merge request !57

remove default duplicity option `--extra-clean`

See merge request !59

sys handler: remove old LUKS header backup file to allow updating

Closes #11333

See merge request !58

solves #11335