[stable29] fix: add break extension to table editor

[benjaminfrueh]

Adds HardBreak extension to PlainTableContentEditor for tiptap v2 to fix Enter key creating malformed HTML in table cells.

[benjaminfrueh]

/backport to stable30

[benjaminfrueh]

/backport to stable31

[benjaminfrueh]

/backport to stable32

[backportbot]

The backport to stable32 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable32
git pull origin stable32

# Create the new backport branch
git checkout -b backport/8169/stable32

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 1415611b

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/8169/stable32

Error: Failed to check for changes with origin/stable32: No changes found in backport branch

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