Support Flat ODF files

[tintou]

• Resolves: Support Flat ODF files #1341
• Target version: master

Summary

Adds missing supported types

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Documentation (manuals or wiki) has been updated or is not required

[juliusknorr]

Did you add some custom mimetype mapping to your nextcloud instance when testing this. As far as I see we currently cannot detect the flat odf mimetype properly within Nextcloud server and using mimetype detection on such a file itself at least for me always brings up text/xml for fodt files.

[juliusknorr]

Pushed a server pull request to make this work properly nextcloud/server#29157

@tintou Could you maybe rebase your branch against current master and push again to trigger the tests again?

[juliusknorr]

@tintou Could you maybe rebase your branch to current master to run the tests again?

[juliusknorr]

I've created a rebase version of your pr in #1811 so we can get this in for Nextcloud 23 (which is required due to the server dependency on the mimetypes nextcloud/server#29157)

[juliusknorr]

Thanks a lot for your pull request and we'll get your commit there merged with the new PR.