feat: Check upload directory share state

[artonge]

Local version of #2657 for CI.

Done:

• Block upload to the album DAV endpoint if the current user does not own the photo folder.
• Add warning in Photos picker dialog. An alternative would be to hide the button. But uploads cannot be blocked as they are done directly to the DAV files endpoint, so it is impossible to distinguish from a legitimate upload.

[artonge]

/backport to stable30

[artonge]

/backport to stable29

[artonge]

/backport to stable28

[artonge]

/backport to stable27

[artonge]

/backport to stable26

[artonge]

/backport to stable25

[artonge]

/compile /

[backportbot]

The backport to stable25 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable25
git pull origin stable25

# Create the new backport branch
git checkout -b backport/2658/stable25

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 3d5562b8 5d116992

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/2658/stable25

Error: No changes found in backport branch

---

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[backportbot]

The backport to stable26 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable26
git pull origin stable26

# Create the new backport branch
git checkout -b backport/2658/stable26

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 3d5562b8 5d116992

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/2658/stable26

Error: No changes found in backport branch

---

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.