Always focus href entry after using mod-k keyboard shortcut

Describe the bug
The behavior of mod-k is still inconsistent.
In particular it will not focus the link entry
if the href already was falsy - for example right after the start.
(Follow up for #7599 )

To Reproduce
Steps to reproduce the behavior:

1. Open a new text document.
2. Enter some word.
3. Select the word (mod-a) and turn it into a link (mod-k)
4. See that the link entry does not receive focus.

It works after showing the link bubble for a link with an actual href.
It does not work directly after showing the link bubble for a link with an empty href.

Expected behavior
Whenever the shortcut is used link bubble should open with the link text entry focussed.

Server details:

• Nextcloud version: 31, 32

Client details:

• Browser: tested with Electron and FF
• Device: Desktop

There are no errors in the relevant logs.
It's just that key inside the LinkBubbleView stays the same so the watcher does not trigger.