Appdata related patches

[yakushabb]

appdata: translate=no properties

It appears that the appstream project no longer supports translatable=no properties, and gettext extract them as translatable.

I opened an issue to inform about the situation, but translatable=no properties are not accepted by developers. You can find the issue here: `https://github.com/ximion/appstream/issues/623

Please test your script or string extraction process before merging this PR.

In MetaInfo files, each individual paragraph of a description (or enumerated entry) is translated individually, however, you can only exclude the complete block from being translated by adding translate="no" to the description element.

Source: https://freedesktop.org/software/appstream/docs/sect-Quickstart-Translation.html

appdata: Add developer ID

Flathub requires a developer tag and developer ID. Also Appstream decided to use rdns structure for developer ID.

It allows reverse-dns IDs like sh.cozy, de.geigi or Fediverse handle (like @[email protected])

A developer tag with a name child tag must be present. Only one developer tag is allowed and the name tag also must be present only once in untranslated form.

<developer id="tld.vendor">
  <name>Developer name</name>
</developer>

Source: https://docs.flathub.org/docs/for-app-authors/metainfo-guidelines/#name-summary-and-developer-name

The element should have a id property, containing a unique ID to identify the component developer / development team. It is recommended to use a reverse-DNS name, like org.gnome or io.github.ximion, or a Fediverse handle (like @[email protected]) as ID to achieve a higher chance of uniqueness.

Source: https://www.freedesktop.org/software/appstream/docs/chap-Metadata.html#tag-developer