Update appstream deprecated tag

1. as per appstream specs the <mimetypes/> tag is deprecated and corresponding tags should be provided in a <mediatype/> tag in the <provides/> tag This was reported by Appstream data for Debian (page may be out of date at future time and not report the issue anymore)
2. The screenshots referenced old urls from version 1.3.* I updated them to the 2.0 while they seems to be a little outdated
3. I added the tags which should refer to gettext domains used by the application. I very looked shortly over the source code so I may have missed some of the domains used.

The appstream file does not validate or validate strictly the specifications:

$ appstream-util validate-strict paperwork-gtk/src/paperwork_gtk/data/work.openpaper.Paperwork.appdata.xml
paperwork-gtk/src/paperwork_gtk/data/work.openpaper.Paperwork.appdata.xml: FAILED:
• value-missing         : <!-- Copyright [year] [name] --> is not present
• attribute-invalid     : <screenshot> width (429) too small [https://gitlab.gnome.org/World/OpenPaperwork/paperwork-screenshots/-/raw/master/2.0/doclist.png] minimum is 624px
• aspect-ratio-invalid  : <screenshot> aspect ratio not 16:9 [https://gitlab.gnome.org/World/OpenPaperwork/paperwork-screenshots/-/raw/master/2.0/doclist.png]
• aspect-ratio-invalid  : <screenshot> aspect ratio not 16:9 [https://gitlab.gnome.org/World/OpenPaperwork/paperwork-screenshots/-/raw/master/2.0/paperwork_export.png]
• attribute-invalid     : <screenshot> width (356) too small [https://gitlab.gnome.org/World/OpenPaperwork/paperwork-screenshots/-/raw/master/2.0/multiple_labels.png] minimum is 624px
• aspect-ratio-invalid  : <screenshot> aspect ratio not 16:9 [https://gitlab.gnome.org/World/OpenPaperwork/paperwork-screenshots/-/raw/master/2.0/multiple_labels.png]
• aspect-ratio-invalid  : <screenshot> aspect ratio not 16:9 [https://gitlab.gnome.org/World/OpenPaperwork/paperwork-screenshots/-/raw/master/2.0/paperwork_page.png]
• attribute-invalid     : <screenshot> width (602) too small [https://gitlab.gnome.org/World/OpenPaperwork/paperwork-screenshots/-/raw/master/2.0/settings.png] minimum is 624px
• aspect-ratio-invalid  : <screenshot> aspect ratio not 16:9 [https://gitlab.gnome.org/World/OpenPaperwork/paperwork-screenshots/-/raw/master/2.0/settings.png]
• attribute-invalid     : <screenshot> width (325) too small [https://gitlab.gnome.org/World/OpenPaperwork/paperwork-screenshots/-/raw/master/2.0/suggestions.png] minimum is 624px
• aspect-ratio-invalid  : <screenshot> aspect ratio not 16:9 [https://gitlab.gnome.org/World/OpenPaperwork/paperwork-screenshots/-/raw/master/2.0/suggestions.png]
• translations-required  : <name> has no translations
Validation of files failed

$ appstream-util validate paperwork-gtk/src/paperwork_gtk/data/work.openpaper.Paperwork.appdata.xml
paperwork-gtk/src/paperwork_gtk/data/work.openpaper.Paperwork.appdata.xml: FAILED:
• attribute-invalid     : <screenshot> width (429) too small [https://gitlab.gnome.org/World/OpenPaperwork/paperwork-screenshots/-/raw/master/2.0/doclist.png] minimum is 624px
• attribute-invalid     : <screenshot> width (356) too small [https://gitlab.gnome.org/World/OpenPaperwork/paperwork-screenshots/-/raw/master/2.0/multiple_labels.png] minimum is 624px
• attribute-invalid     : <screenshot> width (602) too small [https://gitlab.gnome.org/World/OpenPaperwork/paperwork-screenshots/-/raw/master/2.0/settings.png] minimum is 624px
• attribute-invalid     : <screenshot> width (325) too small [https://gitlab.gnome.org/World/OpenPaperwork/paperwork-screenshots/-/raw/master/2.0/suggestions.png] minimum is 624px
Validation of files failed

but it validates "relaxly" (good enough):

$ appstream-util validate-relax paperwork-gtk/src/paperwork_gtk/data/work.openpaper.Paperwork.appdata.xml 
paperwork-gtk/src/paperwork_gtk/data/work.openpaper.Paperwork.appdata.xml: OK