Fix pinning the balloons to #text nodes

[Mati365]

Suggested merge commit message (convention)

Fix (ui): Restored the ability to pin balloons to text nodes in the DOM tree. Closes #16958 #16889.

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Additional information

1. Introduced in Image contextual toolbar does not disappear after clicking source editing. #16739 , we added visibility check before mounting of tooltips to avoid displaying them on hidden elements (which was causing another issue).
2. Regression was caused by isVisible function. It was returning false for $text nodes, so it was impossible to pin balloons to such nodes.
3. I extracted docs example to standalone manual test. Apply this patch to your git repo to test it on your own pin-balloons-demo.patch

Before

before-pin-fix-2024-08-22_08.47.00.mp4

After

after-pin-fix-2024-08-22_08.44.42.mp4

[Witoso]

Does it potentially fix this scenario: #16889 as well?

[Mati365]

@Witoso Most likely.

[niegowski]

We use the nodeType property of a DOM node to verify node type.