App provider create files

[kulmann]

In order to avoid another rebase and review cycle this PR supersedes #5890

Description

Allow creation of files for mimetypes with set flag "allow_creation"

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Technical debt
• Tests

Checklist:

• Code changes
• Unit tests added
• Acceptance tests added
• Documentation ticket raised:

[update-docs]

Thanks for opening this pull request! The maintainers of this repository would appreciate it if you would create a changelog item based on your changes.

[ownclouders]

Results for oC10SharingIntGroups https://drone.owncloud.com/owncloud/web/22166/28/1
The following scenarios passed on retry:

• webUISharingInternalGroups/shareWithGroups.feature:255

[ownclouders]

Results for oC10SharingAccept https://drone.owncloud.com/owncloud/web/22166/15/1

💥 The acceptance tests failed on retry. Please find the screenshots inside ...

webUISharingAcceptSharesToRoot-acceptShares_feature-L108.png

💥 The acceptance tests pipeline failed. The build has been cancelled.

[sonarcloud]

SonarCloud Quality Gate failed.   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
2 Code Smells

12.2% Coverage
0.0% Duplication

[kulmann]

Code is not mine - if I could approve, I'd do it now. There is a backend issue, as described in #5890 - merging anyway to get the functionality in and not be blocked by the backend issue.