Closes: #898999

 * Add tests for fixes of argument injection.

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In DDE, a tools called `dde-open` is used to open preferred app.

DDE use `Deepin` as a desktop name currently,
but in some older version, it was `DEEPIN` or `deepin`

dde-open is provide by dde-api, see [1].

[1]: https://cr.deepin.io/c/dde/dde-api/+/33751

patch courtesy of Simon Lees (SUSE) <sflees@suse.de>

BUG: 106343

Commit 6387086e introduced LXQt support.
In xdg-open it assumed that LXQt and LXDE are the same. They aren't. LXQt
does not have pcmanfm, it has pcmanfm-qt.
LXQt doesn't want to rely on pcmamfm-qt to handle it: LXQt is very modular
and can be deployed without pcmanfm-qt.

open_generic() works for LXQt but it depends on mimeopen and mimetype. In
the future we will want, for sure, to drop those dependencies. That's the
reason for the existence of open_lxqt().

Credit to Ville Skyttä <ville.skytta@iki.fi>

There were no changes to the upstream code but mine. So I modified the
header to clarify the current situation.

Closes: #877747

See: https://bugs.freedesktop.org/show_bug.cgi?id=101640

 * Add some comments into d/rules
 * Create debian/.gitignore file

 * Bump standards version, no changes for this
 * Bump debhelper version
 * Clarify build dependencies
 * Use secure URL for Vcs-* and Homepage fields

 * New maintainer: Debian freedesktop.org team
 * New uploader: Nicholas Guriev