fix: Reuse Viewer's slideshow feature

[artonge]

Instead of reimplementing it. This fix displaying videos in slideshows.

• Needs feat: Support auto-starting slideshow viewer#3350

🤖 AI (if applicable)

• The content of this PR was partly or fully generated using AI

[artonge]

/backport to stable35

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[artonge]

CI fialure unrelated

[backportbot]

The backport to stable35 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable35
git pull origin stable35

# Create the new backport branch
git checkout -b backport/3826/stable35

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 3fc145b0

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/3826/stable35

Error: Failed to clone repository: Failed to create working tree: error: RPC failed; HTTP 401 curl 22 The requested URL returned error: 401
fatal: expected flush after ref listing

---

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

[susnux]

/backport to stable35

[backportbot]

The backport to stable35 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable35
git pull origin stable35

# Create the new backport branch
git checkout -b backport/3826/stable35

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 3fc145b0

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/3826/stable35

Error: Failed to clone repository: Failed to create working tree: error: RPC failed; HTTP 401 curl 22 The requested URL returned error: 401
fatal: expected flush after ref listing

---

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